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 1 Chapter – 1: - REPRODUCTION IN ORGANISMS
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REPRODUCTION IN ORGANISMS
Life Span
Period from birth till natural death.Every organism lives only for certain period of time Eg
Elephant 60 -90 years, Fruit fly 4-5 weeks.
Every organism live only for a certain period of time.
• Reproduction –Producing young-ones of their kind, generation after generation.
• Types of reproduction:
• Asexual reproduction :single parent capable of producing offspring.Somatogenic reproduction
• Sexual reproduction :two parents are invovled in producing offspring.
Modes of asexual reproduction
ƒ Binary fission: parent body divides into two halves, genetically identical to parent.
Amoeba: It is simple or irregular. Paramoecium: Transverse binary fission. Organisms considered
immortal
ƒ Multiple fission: parent body divides into many daughter organisms : Plasmodium.
ƒ Budding: daughter organisms grow from small buds arising in parent body.
Exogenous budding: out side the body eg. Hydra, Yeast.
Budding in Yeast Endogenous budding : inside the body eg. Gemmule in sponge. Oidia of rhizopus
ƒ Conidia: non-motile, exogenous spores in chains eg. Fungi.
ƒ Zoospores: microscopic motile structures eg. Algae. In plants : term vegetative reproduction
frequently used instead of asexual reproduction, units of vegetative propagation called
vegetative propagules.Eg runner, rhizome, sucker, tuber offset, bulb give rise to new plant
ƒ All organisms show remarkable similarity. Vast difference in their reproductive structure. Similar
pattern or phases in their life cycles
ƒ PHASES OF LIFE SPAN.
ƒ Juvenile phase: The phase of growth before reproductive maturity.
ƒ Reproductive phase: Reproductive maturity.
ƒ Senescent phase: Phase between reproductive maturity and death.
¾ Th
i
t
f
l
l
™ Unisexual term used for Heterothallic and Dioecious plants
Male and female reproductive-structure on different plants.
Flowering plants – male flower–staminate flower and female flower–pistillate flower eg. papaya
and date-palm.
• Animals – Bisexual term is used for Hermaphrodite animals-eg. Earth-worm, Tape-worm,
Leech, Sponge.
• Unisexual animals have male & female sexes in separate individuals-e.g. insects, frogs,
humanbeings
Cell division during gamete formation:
Haploid-parent (n) produces haploid gametes (n) by mitotic division, eg. Monera,fungi, algae and
bryophytes.
Diploid parent (2n) produces haploid gametes(n) by meiosis division (possess only one set of
chromosomes)and such specialized parent cell is called meiocyte or gamete mother cell.
• ExampleName of organism
Meiocyte(2n)
gamete (n)
Human
46
23
Housefly
12
6
Ophioglossum (fern)
1260
630
Potato
48
24
b) Gamete transfer:- to facilitate fusion.
™ Male gametes mostly motile and female non-motile, exception few fungi and in algae both gametes
are motile in some cases
™ Water medium for gamete transfer- in lower plants. Large number of male gametes produced to
compensate loss
™ Higher plants, pollen-grains are transferred by pollination.
™ Fertilization: Fusion of male and female gametes diploid zygote.
™ Parthenogenesis.-development into new organism without fertilisation eg. Rotifers, honey-bees,
some lizard, bird(turkey).
Fertilization
Two types- external and internal .
• External fertilisation- outside the body of organism in external- medium (water) eg. majority of
algae, fishes, amphibians.
Post -fertilisation events- formation of zygote.
a. Zygote. One celled , diploid, vital link between two generations.
•
•
External fertilization –zygote formed in external medium water eg. Frog,
Internal fertilization –zygote formed inside the body eg. Humanbeings. Development of zygote
depends on type of life cycle and environment. Some develop thick wall ( prevent damage and
desiccation) & undergo period of rest eg. Algae, fungi.
• Haplontic life cycle- zygote (2n) divides by meiosis to form haploid (n) spores.
• Diplontic life-cycle- zygote (2n) divides mitotically, develops into embryo (2n).
• Oviparous animals lay eggs out-side the female body.Eggs can be fertilized/ unfertilized. Fertilized
eggs covered which hard calcareous shell, laid in safe place in the environment. Unfertilised eggs
laid in water. Example- fishes, frogs, reptiles, birds
• Viviparous animals bear and rear the embryo inside female body, give birth to youngones.Advantage- proper embryonic care, protection, survival chances of young-ones greater.
Example- cows, whales, humanbeings
• Embryogenesis: development of embryo from zygote by cell division (mitosis) and cell
differentiation.
¾ Cell- division increases the number of cells in the developing embryo
Cell differentiation - groups of cells undergo certain modifications for the formation of different
kinds of tissues and organs.
• In flowering plants- zygote formed inside ovule
™ Changes occur in flowering plants:
Sepal
Fall off
Petal
Fall off
Stamen
Fall off
Zygote
Embryo
Primary endosperm nucleus
Endosperm (3 N)
Synergid
Disintegrate
Antipodals
Disintegrate
Ovary
Fruit
Ovule
Seed
Ovary wall
Pericarp (epicarp + mesocarp + endocarp)
Integument
Seed coat (testa + tegmen)
Chapter 1: REPRODUCTION IN ORGANISMS QUESTIONS Q) What is meiocyte? Ans) It is the gamete mother cells which undergoes meiosis. Q) Why is date palm referred to as dioecious? Ans) In date palm the male and female flowers are present in different plants. Q) What is special in flowering in bamboo? Ans) Bamboo flowers only once in their life time generally after 50‐100 years . Q) Define clone? Ans) It is a group of individual of the same species that are morphologically and genetically similar. Q) What is vegetative propagule? Ans) The units of vegetative propargations that gives rise to a new plant is called vegetative propagule. Examples: Runner and rhizome. Q) Digramatically represents asexually reproduction in yeast? Ans) See Figure 1.2 (page‐5) Q) Cucur bit are called monoecious. Justify? Ans) They have male and female reproductive structures in different flowers. Q) If chromosomes number in meiocyte in rat, elephant and rice is 42,56,24 what will be the chromosomes number in theier gamet? Ans) Rat 21, elephant 28,rice 12 3 marks Q) Why higher organisms have resorted to sexual reproduction in spite of its complexcity? Ans) 1. It brings about variations. 2. Variation helps in better adaptation in nature. 3. Variation is the basis of evolution. Q) What is parthenogenesis. Give Example? Ans) Development of a new individual from an unfertilized egg is called parthenogenesis It is simpler easier and rapid mode of replication But there is
5 Marks. Q) What are vegetative propagules. Name any four of them and give example? Eg.‐ rhizome of ginger, leaf bud of bryophyllum, bulb of onion, offset of pistia. HOTS. Q)Amoeba is immortal. Explain? Ans) Amobea has no natural death. It undergoes binary fission and forms two new daughter cells. Q) Which is the first diploid single cell which begins life? Ans) Zygote. Q What is the fate of zygote in organism which show 1 Haplontic life cycle 2Diplontic life cycle Ans In haplontic life cycle zygote undergoes meiosis during its generation In diplontic life cycle zygote divides mitotically during embryogenesis Q) What type gamete are formed in staminate and pistillate flowers? Ans) Pollen grains and egg cell respectively. Q) Name the organisms with respect to their sexuality? i) Monoecious animal ii) Dioecious animal iii) Monoecious plant iv) Dioecious plant Ans :‐ i) Earthworm ii) Cockroach iii) Chara iv) Marchantia. CHAPTER‐ 2 Sexual reproduction in flowering plants
8-1
7 CHAPTER 2 – SEXUAL REPRODUCTION INFLOWERING PLANTS
FLOWERS
Site of sexual Reproduction.
Male and female reproductive organs are borne on flowers.
PARTS OF A FLOWER:
Four whorls – calyx (sepals), corolla (petals), androecium (Male
reproductive organ), gynoecium (Female reproductive organs)
Function of calyx:protects the bud.
Function of corolla :attracts insects by its colour
Male Reproductive Organ
Androecium consists of Stamens.
Stamen consists of anther, filament & connective (when anther is bilobed)
Anther bilobedhas 4 Microsporangia.
Refer fig. 2.1 of NCERT (L.S. OF A FLOWER WITH DIFFERENT PARTS)
MICROSPOROGENESIS:The process of formation of micro spores from pollen mother cell through
meiosis iscalled microsprogenesis.
Tapetum :Inner most layer of wall of microsporangium .Cells have dense cytoplasm. Generally have more than
one nucleus .Nourishes the developing pollen grain
Microspore mother cell (2n)
Meiosis
Microspore (n)
Mitosis
Pollen grains (n)
LAYERS OF ANTHER WALL
Pollen grains have two outer walls; i) Exine ii) Intine
Exine is made of sporopollenin.(Hardest natural substance). Intine is made of cellulose
and pectin.
Mature pollen grains have two cells – largevegetative cell & small generative cell.
Generative cell forms two male gametes bymitotic
division.
Pollen grains (Refer fig 2.7 of text book)shed in 2-celled /
3celled stage
See Fig 2 5 a and b page 23
Megasporogenesis
Megaspore mother cell (2n)
Meiosis
4 Megaspores (n)
(3 megaspores degenerate, 1 remains functional)
Funtional Megaspore (n) (Divides 3times by mitosis)
8 Nucleated Embryo Sac formed
3 cells group at micropylar end -the egg cell(n) & 2 synergids(n)
3 cells at chalazal end called antipodals(n)
2 polar nuclei at center(n each )
Embryo sac
Ref fig 2.7 and 2.8 of text book
POLLINATION– transfer of pollen from anther to stigma. Agents of pollination –air, water,
insect.bat,bird,man.
Transfer of pollen
to stigma
Self pollination
(Autogamy)
Cross pollination (Hetrogamy)
Geitenogamy
Auto gamy
Xenogamy (different flowers on
different plants of the same
species)
Syngamy: Fusion of one male gamete(n) with egg (n) Zygote(2n)Produced
First Fusion
Fusion of two Polar Nuclei(n+n=2n)
Second fusion.
Male Gamete(n) Fuses with the fusion product of the two polar nuclei(3n)Third Fusion
fusion of male gamete with egg cell.
Double fertilization: i)Fusion of male gamete with egg – First fertilization ,SYNGAMY
ii)Fusion of fusion product of polar nuclei with male gamete – Second fertilization .TRIPLE FUSION
Refer fig 2.13 in NCERT
Post fertilisation changes:
Stages of embryo development after fertilization:
1. Zygote divides by mitosis into suspensor & embryo cells
2. Suspensor cell forms a globular basal cell which remains
embedded in the endosperm & a
multicellular suspensor bearing the embryo
3.Globular embryo becomes heart-shaped & then mature
embryo with radicle, plumule&Cotyledons
Primary endosperm nucleus – divides repeatedly to form
endosperm, food for theembryo.
Mature ovary becomes fruit.
Mature ovule becomes seed.
True Fruit develops only from the ovary, e.g. mango, tomato
False Fruit develops from parts of the flowerother than the
ovary e.g. apple, peach etc.
Seeds two types: i) Albuminous (with Endosperm)
ii) Non albuminous(without Endosperm)
Special mechanism of reproduction:I) Apomixis- Production of seeds without fertilisation e.g.
species of Astereceae and grasses.
ii) Polyembryony- Occurrence of more than one embryo in a
seed e.g.Orange.
Outbreeding devices:
Types of cross-pollination performed by man for cropimprovement. Achieved by
i) Emasculation i.e. removal of anthers from the flower bud of a bisexual flower before the anther
dehisces using a pair of forceps and
ii) Bagging i.e. covering the emasculated flowers with a bag of suitable size to protect them from
contamination with unwanted pollen
If flower is unisexual, emasculation is notneeded. Flower bud bagged & when the stigmabecomes
receptive, pollination is done using desired pollen & the flower is rebagged
Pollen –pistil Interaction i) All the events from pollen deposition on the stigma until the entry of the pollen tube into the ovule are together called pollen‐pistil interaction. ii) It is a dynamic process involving pollen recognition by stigma/pistil for compatible pollen by accepting them and if incompatible rejecting them. Chapter-3 HUMAN REPRODUCTION
Ref.: Concept map: Page-C1 & C2
The Male reproductive system
1. Penis
a. Urination
b. Sexual intercourse
1. Corpus cavernosum- spongy tissue that fills with blood to make penis erect
2. Glans- the head, end of penis
3. Foreskin
i. Covers glans,
ii. May be removed surgically in an operation (circumcision)
2. Scrotum
a. Located behind penis
b. Contains two testes
c. Temperature sensitive (Sperm must be made in cooler conditions i.e, 2-3° C
lower than body temperature)
3. Testes
a. Sperm is produced by the seminiferous tubules due to FSH
b. Testosterone is produced by Leydig cells due to LH
1. Causes the development of the male sex organs at ~8 weeks after
conception.
2. Responsible for facial, armpit, and pubic hair, bone growth and muscular
development.
c. Testes formed in the abdomen before birth. Descend through the "inguinal
canal" during fetal or post-natal life. Sometimes it may take months/years to
reach right place. Possible site for hernia.
4. Epididymis:
Stores sperm until they have matured.
5 Vas deferens:
Tube that leads from the epididymis to the urethra
The Female Reproductive System
Ovary:
i) Each ovary contains immature ova (eggs) in follicles.
ii) Females born with lifetime supply of eggs(250,000-400,000 in each ovary)
iii) Ovaries release ovum -. Almost all ova degenerate between birth and puberty.
iv) Approx. 400 eggs will be ovulated over woman's life.
v) Egg is the largest human cell.
vi) Ovaries are located lower abdomen. 1 left and 1 on the right.
Fallopian tubes
i)Two thin tubes attached to the upper sides of uterus
ii) Tubes terminate near the ovaries but are not attached
iii)"Fimbriae" are finger-like structures on the end of each tube
iv)Tubes conduct egg to uterus by use of small hairs called "cilia"
v)Fertilization of ovum takes place in the ampullary-isthmic junction of the fallopian tubes. Egg
viable for only 24-48 hours after ovulation.
Uterus:
i)Pear-shaped organ located in lower abdomen
ii)Muscles(myometrium) stretch to allow baby to develop. Oxytocin starts labor contractions.
iii)Lining of uterus (endometrium) thickens with blood-rich tissue due to progesterone
iv)Endometrium supports embryo/fetus during growth
v)Placenta It is the interface between baby and mother. If not pregnant, lining breaks down and is
discharged from body through vagina. This is menstruation (period)
Cervix:
i)Located at inner end of vagina
ii)Opening of uterus into vagina
iii) Mucous prevents bacteria and viruses from entering uterus
iv)Lets sperm into uterus after ovulation
v) Where baby also passes through during vaginal birth
Labia:
2 layers of skin, which fold over the opening to vagina and urethra
ii) Inner labia (labia minora)
iii)Outer labia (labia majora)
1.Two folds of skin, surround vaginal area
2. Pubic hair grows on outer labia
Clitoris:
i) Small organ, 5 to 10 millimeters long
ii) Located at junction of inner labia near front of body
iii) Contains erectile tissue& sexually sensitive
Mons pubis :Cushion like fatty tissue covered by skin and pubic hair
Gametogenesis & its hormonal regulation :
Ref: Concept Map Page C 3
Differentiate between: Spermatogenesis and Oogenesis :
Spermatogenesis
Oogenesis
Produces male gametes (sperm)
produces female gametes (oocytes)
–occurs in the seminiferous tubules (in testes)
–occurs in the ovaries
–involves meiosis
–occurs throughout life after puberty
– involves meiosis
occurs after puberty until menopause
may produce 400,000,000 per day
–humans normally produce one oocyte during
each ovarian cycle
Primary spermatocyte divide equally to form two
Primary otocyte divide unequally to form one
2)Follicular phase (Proliferative phase ) and Luteal phase (Secretory Phase)
Proliferative phase
Secretory Phase
Follicular phase
Luteal phase
Stage of repair and proliferation
Prepares endometrium for implantation
It extends from the end of menstruation to ovulation
It extends after ovulation to menstruation
LH and FSH increases
LH is high (LH surge)
Estrogen level increases
Progesterone level increases
Estrogen is secreted by Graffian follicle
Progesterone secreted by corpus luteum
Menstrual Cycle
MenstruationÆ
Repair of the
endometriumÆ
Follicular Phase
FSH/Estrogen
OvulationÆ
Due to LH
Thickening of the
endometriumÆ
Breaking
downÆ
Luteal Phase
LH/Progesterone
MENSTRUAL CYCLE: Ref. Concept Map Page C 4 Functional Activities of FSH and LH
FSH and LH from the pituitary:
FUNCTION
/ PRODUCTION
Hormone
In Females
In Males
FSH Controls Æ
Eggs + Estrogen
Spermatogenesis
LH Controls Æ
Ovulation +
Corpus Luteum
Testosterone
DEVELOPMENT OF OVARIAN FOLLICLE
From Primordial Follicle to Tertiary Follicle
Primordial follicle:The surviving primary oocytes, at birth, are surrounded by thin, single layers cells
of so-called follicular epithelial cells.
Primary follicle
The primordial follicles while developing into primary follicles the follicular epithelium that surrounds the
oocyte becomes iso- to highly prismatic
Secondary follicle
Secondary follicles with follicular epitheliums encompassing multiple rows are formed called the
stratum granulosum. Pellucid zone, between the oocyte and follicular epithelium becomes visible.
Tertiary follicle
A well-developed net of capillaries in the theca interna.
Antrum – a fluid filled cavity develops
The theca layer organized into Theca internal & Theca external
Tertiary follicle
EMBRYONIC DEVELOPMENT
Ref.: Concept Map- C5
1
2
3
4
5
6
7
8
Oocyte
Pellucid zone
Stratum granulosum
Theca internal
Theca external
Antral follicle
Cumulus oophorus (Granulosa cells, together with the oocyte)
Basal lamina between theca and stratum granulosum
Conception to Birth
The following shows some of the many stages of human development:
Zygote
The single cellthat results from
fertilization of an ovum by asperm.
Blastocyst
Embryo
The blastocyst is a liquid-filled ball of
cells. Occurs around 5 – 8 days after
conception. Implantation in the
endometrium occurs at this stage.
Human considered an embryo from
implantation until about 8 weeks after
conception.
Foetus
8 weeks after conception until birth.
Fate of three germ layers
Ectoderm
Mesoderm
Endoderm
Nervous system
Skeleton
Digestive tract
Epidermis of skin
Muscles
Respiratory system
Circulatory system
Liver, pancreas
Gonads
Bladder
Mnemonics
Tubules in male reproductive system
“SEVEN UP”
Seminiferous tubules
Epididymis
Vas deferens,
Ejaculatory duct
(Nothing)
Urethra
Penis
Menstrual Cycle
“FOL(d) M(a)PS”
Ovarian cycle:
Follicular phase
Ovulatory phase
Luteal phase
Menstrual cycle:
Menstrual flow,
Proliferative phase
Secretory phase
TERMS TO REMEMBER
Acrosome- the part of a sperm cell that contains an enzyme – (This enables a sperm cell to penetrate an egg.)
Afterbirth-placenta and fetal membrane expelled from the uterus after the birth of a baby
Amniotic sac-fluid-filled membrane or sac that surrounds the developing embryo while in the
uterus.(protects baby from hard shocks, keeps it at a constant temperature. )
Birth-the process of being born.Process by which baby moves from the uterus into the outside
world.Parturition
Blastocyst = blastula = early stage of an embryo; a liquid-filled sphere whose wall is composed of a
single layer of cells; during this stage (about eight days after fertilization) implantation in the wall of the
Endometrium - the lining for the uterus – site for blastocyst implants and develops.
Epididymis-the tightly coiled tube at the back at each testis that holds newly created sperm – (each
epididymis is like a nursery where sperm mature and learn to swim.)
Erection- condition of penis when it fills with blood and becomes firm, enlarged, and erect.
Fallopian tubes -tubes leading from each ovary to the uterus. Tubes carry the egg from ovary to the
uterus. Fertilization occurs here. (Also known as the oviducts.)
Fimbria - A fimbria (plural fimbriae) Latin word, literally means "fringe." a fringe of tissue near the
ovary leading to the fallopian tube
Fertile- able to conceive a child
Fertilization union of sperm and egg.Conception.
Fertilized egg- egg after sperm has united with it. Zygote.
Fetus-unborn child developing in the uterus after the first eight weeks of life
Follicle - In ovaries. Each holds and nourishes an egg until ovulation. Nest. Becomes corpus luteum
after ovulation.
Foreskin – A sheath of skin that surrounds the penis.
Follicle Stimulating Hormone - secreted from pituitary gland in both men and women. In women,
FSH promotes the development of eggs and estrogen. In men, FSH promotes the development of
sperm cells.
Fraternal twins-babies that develop from two eggs, each fertilized by a sperm cell; may or may not
be of the same sex
Gamete – a sex cell. Sperm cells and egg cells are gametes.
Genitals-the reproductive or sex organs, especially the external organs
Germ Cell- egg or sperm cell.Gamete. In humans, germ cell contains 23 chromosomes
Hormones-chemical substances produced by the endocrine glands; they act in other parts of the
body and affect maturation, growth, and behavior; LH, FSH, GH, Testosterone, Estrogen,
Progesterone are all hormones.
Hymen-a thin bit of tissue, or membrane that may partially cover the opening of the vagina
Identical twins-babies that develop from a single fertilized egg that separates into two halves;
identical twins are always of the same sex
Labia-two folds of skin surrounding the entrance of vagina
Labor-the muscular contractions that expel a baby from uterus during childbirth
Leydig Cells – when prompted by LH, Leydig cells create testosterone.
LH - Luteinizing Hormone - Secreted from pituitary gland, causes ovulation and formation of corpus
Luteum in women. In men, LH causes Leydig cells to produce testosterone.
Menstrual cycle - periodic building up and sloughing off of lining of uterus approximately every
twenty-eight days
Menstruation-the periodic discharge of blood and waste material (unfertilized secondary oocyte / ova
and the degenerating endometrium lining) from the uterus
Placenta- network of blood vessels and other tissues by which the unborn child is attached to the wall
of the uterus.grows out of the endometrium The umbilical cord is attached to it. It is the interface
between mother and developing fetus.
Pregnancy-the process in a woman from conception to birth
Pregnant-the condition of a woman with an embryo or fetus in her uterus
Progesterone – pregnancy hormone, which is first produced by the corpus luteum and then by the
placenta.
* increases lining of endometrium.
*maintains pregnancy
*helps develop mammary glands.
Prostate gland- surrounds the upper end of male urethra and produces part of the fluid that mixes
with the sperm to form semen. Prostate fluid alkaline helps to protect sperm from vaginal acids.
Scrotum- pouch of loose skin containing the testes.Houses and air-conditions the testicles by moving
and sweating.
Semen-the mixture of sperm and fluids released during ejaculation. Semen comprised of sperm,
fructose, prostate fluid and oil from Cowper’s gland.
Seminal vesicles-small saclike organs opening into each vas deferens near the upper end of the
urethra; produce part of the fluid that mixes with the sperm to form semen; provide food (fructose) for
the sperm.
Seminiferous tubules - tubes in testes that produce sperm
Sexual intercourse- entry of penis into vagina and subsequent release of semen; also called coitus
Sperm-the male sex cell (male gamete or spermatozoon), which contains 23 chromosomes in human.
Spermatozoon-scientific name for sperm
Spontaneous abortion--synonym for miscarriage
Testes- male sex glands; produce sperm cells and testosterone;
Testicles-synonym for testes
Testosterone – male hormone that regulates development of penis, muscles, body hair, change of
voice.
Umbilical cord- ropelike structure connecting embryo or fetus to placenta within the uterus.
Urethra-the tube through which urine is expelled from the bladder in both males and females and
through which semen leaves the male body
Uterus = womb - the hollow pear-shaped organ in which a baby develops before it is born;
Vagina- passage from the uterus to the outside of the body, accepts the penis during intercourse. It is
the birth canal & menstrual fluids leave through it
Vas deferens- tube extending from each epididymis to the urethra in males
Womb-synonym for uterus
Yolk sac-a structure that develops for the nutrition of embryo during early embryonic life and then
ceases to function
IMPORTANT NOTES
•
An adult male produces over 1012 to 1013 sperms each day.
•
Human female oogonial development by mitosis is completed by 25 weeks of foetus and no
oogonia are formed after birth.
•
Sperm entry into the ovum stimulates MPF (M phase promoting factor) & APC ( Anaphase
promoting complex) for completion of Meiosis II.
•
During Spermatogenesis, spermatogonium produces four sperms while in oogenesis,
oogonium produces one ovum and two polar bodies.
•
Human Sperm contains Clupein proteins.
•
Yolk nucleus: A mass of mitochondria and golgi bodies near nucleus is called as yolk nucleus
and controls vitellogenesis.
•
Maximum level of estrogen – 12th day, LH-13th day, Progestrone – 21st day, Corpous luteum
formation – 19th day of menstrual cycle.
•
Menstrual cycle is absent during pregnancy, lactation periods and permanently during
menopose.
•
Two ovaries alternate in ovulation.
•
13 mature eggs are released per year, so about 416 eggs (13x32 years) are ovulated during
whole reproductive period of human female.
•
Menstruation is also called “Weeping of uterus for the lost ovum” or” Funeral of unfertilized
eggs”.
•
In human embryo, yolk sac degenerates since eggs is microlecithal, which shows evolutionary
significance.
•
Placenta acts as a physiological barriers and an ultra-filter between foetal and maternal blood.
•
Progesterone is also called pregnancy hormone since its secretions controls pregnancy.
1) Zygote undergoes mitosis to form 16 celled embryo. What is the stage known as?
(1) Hint-Blastomeres.
2)Name the important mammary gland secretions that help in resistance of the new born
baby. 1)
Hint-Colostrum
3) Fill in the boxes
Spermatogenesis
Secondary spermatocytes
Spermatozoa
4) Why does fertilization take place in fallopian tube and not in the uterus.(2)
Hint-ovum and sperms must be transported to the ampullary –isthmic region simultaneously
for fertilization.
5) Which cell organelle is present in the neck of the sperm? What is its significance? ( 2)
Hint-Acrosome, enzymes.
6) Give Hormonal regulation for spermatogenesis? (5 )
HintÆ LH
Leydig’s cell
synthesis of
androgen (Testosterone)
Stimulates
spermatogenesis
HYPOTHALAMUS
Increased
Activates
secretion of
Anterior
GnRH
Pituitary
Hypothalamus
Release ofGnRH
Activates anterior pituitary,secretes
L.H
FSH
Estrogen Ovarian follicle Corpus luteum Estrogen Progesterone. Chapter-4: REPRODUCTIVE HEALTH
Reproductive Health:
Human reproductive health and sexuality involve great many components and interrelationships.
A total view of human reproductive health is basic to personal well-being as well as to
interpersonal relationships.
Every individual is a unique sexual being.
Adolescents are vibrant, fragile and prone to experimentation and risk taking, as a result they are
the most vulnerable population as far as delinquent behavior and attitude is concerned.
Every decision has its own consequence. Any wrong decision can lead to disastrous
consequence, which in turn can ruin one’s life.
Sexual adjustment is part of total personality adjustment. Self-esteem is the key to sexual
maturity.
Broad based community and institutional support for reproductive health is essential.
Adolescence Reproductive and Sexual Health(ARSH) topics are to be taken care of to dispel
the myths and misconception about this important aspect with focus on:
•
•
•
•
•
•
•
Reducing risky behavior
Theories which explain what influences people's sexual choices and behaviour
Reinforced message about sexual behaviour and risk reduction
Providing accurate information about, the risks associated with sexual activity, about
contraception birth control, methods of avoiding or deferring intercourse
Dealing with peer and other social pressures on young people; providing opportunities to
practice communication, negotiation and assertion skills
Uses a variety of approaches to teaching and learning that involve and engage young people
and help them to personalise the information
Uses approaches to teaching and learning which are appropriate to young people's age,
experience and cultural background
Methods of birth control
Rhythm method or Safe Period: Method requires a good knowledge of the female
partner's menstrual cycle to identify the days on which sexual intercourse is possible
without the risk of pregnancy.
Avoiding vaginal Intercourse: Anal sex, oral sex or sex without penetrating the vagina
Barrier methods: In barrier methods of birth control, a barrier is placed between the penis and
the vagina during intercourse so that the sperm cannot meet the ovum for fertilization.
o Male Condoms:, usually made of latex that covers the erect penis during penetration
of the vagina.
o Female Condoms: made of polyurethrane, loose sheath with two rings on either side.
can be inserted about 8 hours prior to sexual intercourse and can be kept in for about
another 12 hours after intercourse. Can be used more than once during this period.
o Condoms protect against pregnancy as well as sexually transmitted diseases
(STDs), including HIV/AIDS.
o Diaphragm: vaginal - a small saucer shaped rubber sheath with a metal coil in its rim
which is fitted across the mouth of the uterus (cervix).
o Cervical Cap: The cervical cap is a small dome-shaped rubber device fitted on the
cervix. It is uncomfortable to apply and is rarely used nowadays.
o Vaginal Sponge: Small polyurethrane round device which needs to be placed inside
the vagina before sexual intercourse. It releases spermicide which makes sperm
inactive. It should be left in place for 8 hours after use and can be used more than
once during this time.
o
•
•
The sponge also acts as a barrier contraceptive to some extent since it swells up to fit
across the cervix once it is inside the vagina.
•
•
Hormonal Methods: Drugs are used to either prevent ovulation or to prevent implantation of
the embryo after fertilization.
Combined oral contraceptives contains two hormones similar to the natural hormones in a
woman’s body---an estrogen and a progestin.
How the Birth Control Pill works
Mainly work by preventing ovulation. In a normal menstrual cycle, the pituitary gland secretes the
hormones FSH and LH to stimulate the ovary to release an egg ('ovulation").
Progesterone in pills make the cervical mucus hostile to the sperm.
The Patch: The patch (Ortho Evra). This is a thin band-aid like patch containing
estrogen and progesterone should be applied over the skin. Releases the hormones
slowly into the skin through which they are absorbed.
o Depo-provera: This birth control method consists of injecting a high dose of the
hormone progesterone every three months. It acts mainly by preventing ovulation. The
main disadvantage is that there may be irregular bleeding throughout the three
months.
o Nuvaring: This is a thin silastic ring which should be inserted into the vagina once
every month. It releases the hormones estrogen and progesterone and prevents
ovulation during the menstrual cycle.
o
Subdermal Implants
The Norplant (a registered trademark of The Population Council for levonorgestrel subdermal
implants) Implant system set of six small plastic capsules. Capsules placed under the skin of a
woman’s upper arm.
Norplant capsules contain aprogestin, similar to natural hormone that a woman’s body makes.
It is released very slowly from all six capsules. Thus the capsules supply a steady, very low
dose. Norplant implants contain no estrogen.
Norplant capsules thicken cervical mucus making it difficult for sperm to pass through. It stops
ovulation (release of eggs from ovaries) in about half of the menstrual cycles after the first year
of use.
Emergency Oral Contraception
After unprotected sex, emergency oral contraception can prevent pregnancy. Sometimes called
postcoital or ‘morning after’ contraception.
Mainly stops ovulation
Regular use of emergency contraceptives has serious health hazards.
Vaginal Pessaries, Tablets, Creams or Foams:
These contain spermicides which are toxic to the sperm and should be inserted into the vagina
just before coitus. Their advantages are that they are easy to apply, do not interfere with coitus
and act as lubricants. Disadvantage is that they are not very effective always.
Intra-Uterine Contraceptive Devices (IUCD):
IUCDs or IUDs are contraceptive devices which are placed inside the uterus. Small, flexible
plastic frame. Has copper wire or copper sleeves on it. Inserted into a woman’s uterus through
her vagina. Have two strings, or threads, tied to them. Strings hang through the opening of the
cervix into the vagina. A provider can remove the IUD by pulling gently on the strings with
f
•
Lippes Loop: The Lippes loop consists of a thin plastic (or polyethylene)wire bent in a series
of S-shapes.
l
Lippes loop
•
•
•
Copper-Ts
Copper T: T-shaped structure which stays inside the uterus with the long arm of the T along
the uterine cavity (endometrium) and the shorter arms transversely across the upper part of the
endometrium.
Mirena:Releases a progesterone called levonorgestrel. Works by affecting ovulation, affecting
the normal growth of the endometrium and by affecting the cervical mucus so that the
movement of sperm is obstructed. In the United Kingdom, hormone based IUDs are known as
Intra-uterine Systems (IUS).
Surgical Methods: These are more
or less permanent methods of
contraception.
o Tubal Ligation: Both the
female tubes are tied off
and usually cut during tubal
ligation to prevent the
sperm from reaching the
ovum during intercourse.
o Vasectomy:The two tubes
which carry sperm from the
HOW PREGNANCY OCCURS
Occurs when a sperm meets with an ovum.
Ovum round about 100 microns in diameter.Ovum picked up by the fallopian tube on the same side.
Tubes have long fingerlike projections called fimbria which it uses, rather like hands to pick up the
ovum. Ovum moves through the tube, propelled along by long hairs growing from cells in the tubes.
Like grass bending before the wind, the hairs bend towards the uterus in waves, pushing the ovum
slowly towards the uterus. The egg remains viable, (alive) for about 72 hours, but is capable of being
fertilized for only about 12 - 24 hours. If it remains unfertilized during this period, it disintegrates in the
tube without leaving any trace. Its end products (mainly proteins) are absorbed into the bloodstream
and excreted through the urine or stool.
Fertilization, Implantation and Pregnancy
Sperm viable for a longer period, found in uterus 5 – 7 days after coitus.But capable of fertilizing an
ovum for only 48 - 72 hours after being ejaculated. Time taken by sperm to reach tubes is between 6 –
12 hours but many authorities say it can be as early as 1 hour.
Intercourse has to take place within this narrow time frame (1-2 days before ovulation or immediately
after ovulation), for a pregnancy to occur. At every intercourse normal man deposits 2 – 5 mililitre of
semen in the upper part of the vagina (see diagram). Each mililitre of semen normally contains about 50
Unsuccessful sperms slowly degenerate, break down and become indistinguishable from any other
protein end product in the female partner’s body (sperm made up mainly of protein). These get
absorbed into the blood stream, are carried away to be expelled from the body in the stool or the urine.
Sperm that manages to penetrate the ovum fuses with it to form a single cell called a zygote. Zygote
starts to divide as it is propelled towards the uterus – dividing first into 2 cells, then into 4, then 8 and so
on. Dividing zygote called an embryo.
When the process of in-vitro fertilization (IVF) is carried out, the ovum and the sperm is allowed to
fertilize in a laboratory dish (petri dish). The embryo is usually transferred into the mother’s uterus at the
4 – 8 celled stage, usually on the third day after fertilization.
By the time the zygote reaches the uterus at about the 6th to 9th day after ovulation, it is a 16-celled
cluster of cells called a morula. The morula looks rather like a bunch of grapes. Each of its cells is
identical to each other.
Theoretically, it is from the 2-celled to the 16-celled stages that the cells can be separated from each
other and allowed to develop into clones of each other (identical twins). In nature, separation occurs
spontaneously – usually at the 2-celled stage – to form identical twins. Separation at later stages can
lead to the potentially fatal condition of conjoint twins or Siamese twins.
When it reaches the uterus, the morula sticks to the inner lining of the uterus (called the 'endometrium').
By this time, the hormone progesterone released by the ovaries finishes preparing the endometrium to
receive the morula.
The morula burrows deep into the endometrium and by the 9th - 12th day after ovulation, is fully buried
INFERTILITY AND ITS TREATMENT
‘Infertility’ when a couple fails to conceive after one year of sexual life without contraception. 80% of all
women desiring children, conceive within 1 year of marriage and another 10% within the second year.
According to the World Health Organisation, incidence of infertility is about 10 % worldwide. Another
10-12% of all the other couples have only one child and wish to have more. The incidence of infertility is
gradually increasing all over the world.
For many people going through infertility treatment, the level of distress and tension can be very high.
Mutual trust and faith in the doctor can help the couples to enquire about different modalities of
treatment for both the male as well as the female partner, and make informed decisions of their
reproductive status azoospermia (complete absence of sperm). In these cases, sperm has been
aspirated from the testes directly.
• Intra-Uterine Insemination (IUI): This method is used in men with moderately low sperm
count. the semen is collected by masturbation, washed and centrifuged to increase the sperm
density. This high density sperm sample is now injected into the uterus, bypassing the vagina.
The chances of hostile cervical mucus is thus eliminated. Since the sperm is injected into the
uterine cavity, chances of pregnancy is increased. The procedure should be done within 2
hours of collecting the semen.
o Insemination with Husband's Semen (AIH)This is done in cases of impenetrable cervical
mucous or when disease or deformity of the cervix makes it impossible for the sperm to enter
the uterus. It is also carried out in cases of impotence or premature ejaculation.
o
Insemination with Donor Semen (AID) AID is usually carried out in couples where the
husband suffers from azoospermia.
InVitro Fertilisation (IVF) process by which egg cells are fertilised by sperm (usually 100,000 sperm /
ml) outside the womb, in vitro. IVF is a major treatment in infertility when other methods of assisted
reproductive technology have failed. The process involves hormonally controlling the ovulatory process,
removing ova (eggs) from the woman's ovaries and letting sperm fertilise them in a fluid medium. The
fertilised egg (zygote) is then transferred to the patient's uterus with the intent to establish a successful
pregnancy. The first successful birth of a "test tube baby", Louise Brown, occurred in 1978. Prior to that,
there was a transient biochemical pregnancy reported by Australian Foxton School researchers in 1973
and an ectopic pregnancy reported by Steptoe and Edwards in 1976.
Takes an average five weeks to complete a cycle of ZIFT. First, the woman must take a fertility
medication to stimulate egg production in the ovaries. The doctor will monitor growth of ovarian follicles,
once they are mature, woman will be injected with human chorionic gonadotropins (hCG). Eggs will be
harvested approximately 36 hours later, usually by transvaginal ovum retrieval. After fertilization in
laboratory resulting early embryos or zygotes are placed into the woman's fallopian tubes using
laparoscope.
Gamete intrafallopian transfer (GIFT) assisted reproductive technology against infertility. Eggs
removed from a woman's ovaries, placed in one of the Fallopian tubes, along with the man's sperm.
The technique, which was pioneered by endocrinologist Ricardo Asch, allows fertilization to take place
inside the woman's body.
Takes, an average of four to six weeks to complete a cycle of GIFT. First, the woman must take a
fertility drug to stimulate egg production in the ovaries. The doctor will monitor growth of ovarian
follicles, once they mature, woman will be injected with Human chorionic gonadotropin (hCG). The eggs
will be harvested approximately 36 hours later, mixed with the man's sperm, and placed back into the
woman's Fallopian tubes using laparoscope.
Intracytoplasmic Sperm Injection (ICSI): technique in which a single sperm injected into the centre of
the egg, in order to achieve fertilization. Sperm is collected from the male partner by masturbation.
Single healthy sperm then injected into the prepared ovum.
The advantage of this method is that only a single sperm is needed - even men with a very low sperm
count can become fathers with this treatment. Men found to be azoospermic, that is with no sperm at all
in the semen, sperm can be suctioned out of the vas deferens ( male tubes). Sperm can also be
liberated from the testes itself by careful testicular biopsy and culture by a method called MESA Microepididymal sperm aspiration.
Prevention of Male Infertility : Undescended testes should be treated at the earliest during infancy
before testicular function is damaged. Infections by mumps and other viruses should be managed by
keeping a watchful eye on complications in the testes.
General Facts About STDs
Sexually transmitted diseases (also called STDs, or STIs for sexually transmitted infections):
Infections transferred from one person to another through sexual contact. According to the Centers
for Disease Control and Prevention, there are over 15 million STD cases reported annually in the
United States. More than 25 diseases that are transmitted through sexual activity. Other than HIV,
the most common STDs in the United States are chlamydia, gonorrhea, syphilis, genital herpes,
human papillomavirus, hepatitis B, trichomoniasis, and bacterial vaginosis. Adolescents and young
adults are the age groups at greatest risk for acquiring an STD. Approximately 19 million new
Herpes Virus: STD that presently with no cure. Treatment available. Home remedies & natural
treatmentavailable. Herpes symptoms include blisters or sores that periodically break out on the
genitals. Refer FAQs.
Hepatitis: To cure for those already infected, a Hepatitis B (HBV) vaccine available to prevent spread
of this infection. Many are asymptomatic, however those who do suffer from Hepatitis B symptoms
may have many unpleasant discomforts. Infection may clear up on its own. Some people may suffer
from chronic infections for many years. Treatment available for chronic sufferers. Other types of
hepatitis infections that can be passed through sexual contact include Hepatitis A and Hepatitis C.
HIV/AIDS: Most dreaded STD. New ways of treating this infection significantly prolongs an infected
person's life. For many this infection eventually progresses to AIDS and, ulitmately, death. More than
40 million people worldwide are infected with the HIV virus; women account for 50% of those infected.
Syphilis: Throughout history, cases of syphilis have been recorded. Can easily be treated and cured.
Without treatment, syphilis symptoms can progress and affect the nervous system and brain leading
to dementia and even death.
Trichomoniasis: most common, curable STDs. However, symptoms may be mistaken for a yeast
infection causing women to use wrong type of treatment for her vaginal discharge.
Common Infections:Chlamydia and gonorrhea often infect a person at the same time. Although the
symptoms of chlamydia are different from gonorrhea not unusual for person to be asymptomatic. If
testing for chlamydia, good idea to test for gonorrhea. Both STDs can be cured but can damage
reproductive system if left untreated.
Pubic Lice:Crabs are very similar to head lice. Itchy symptoms can be hard to miss. Treatment for
pubic lice can easily take care of the discomfort these pests can cause.
Rare Infections:Granuloma inguinale and chancroid,. Other lesser-talked about STDs include
nongonococcal urethritis and molluscum contagiosum,
KNOW THE SYMPTOMS OF STDs
Men
‰
‰
‰
‰
‰
Swelling or tenderness in genital area.
Blisters ,sores or bumps around the mouth or genitals.
Fever,chills and aches.
Unusual itching.
Burning sensation when you pass urine or move your bowels.
Pelvic Inflammatory Disease Overview
Pelvic inflammatory disease (PID) is infection of a woman's reproductive organs. Infection spreads
upward from the cervix to the uterus, Fallopian tubes, ovaries, and surrounding structures
Pelvic Inflammatory Disease (PID) Symptoms
If a woman has PID, she may have any of these symptoms:
• Abdominal pain (especially lower abdominal pain) or tenderness
• Back pain
• Abnormal uterine bleeding
• Unusual or heavy vaginal discharge
• Painful urination
• Painful sexual intercourse
• Symptoms not related to the female reproductive organs include fever, nausea, and vomiting.
PID symptoms may be worse at the end of a menstrual period and during the first several days
following a period.
Ectopic Pregnancy Overview
Pregnancy that develops outside a woman's uterus (womb).When the fertilized egg from ovary does not
implant itself normally in the uterus. Egg develops somewhere else in the abdomen. Such conceptions
are abnormal and cannot develop into a fetus.
• Common ectopic pregnancy in fallopian tubes (so-called tubal pregnancy). Also found on the
outside of the uterus, on the ovaries, or attached to the bowel.
• Complication of ectopic pregnancy is intra-abdominal hemorrhage (severe bleeding). Eg. tubal
pregnancy the products of conception continues to grow in the fallopian tube, tube expands
and eventually ruptures. This can be very dangerous because a large artery runs on the
outside of each fallopian tube. If the artery ruptures, you can bleed severely.
•
Ectopic pregnancy usually found in the first 5-10 weeks of pregnancy.
INFERTILITY IN HUMAN: Causes &Consequences :IN MALES
IN FEMALES
Oligospermia: Low sperm count
Anovulation: Absence of ovulation.
Azospermia: Absence of sperm.
Oligoovulation: Deficient ovulation.
Asthenozoospermia: Low sperm motility.
Teratozoospermia: Defective sperm
Hyperprolactinemia: Ovum remain trapped
inside the follicle.
Idiopathic Infertility: Failure or abnormal
COMMON SEXUALLY TRANSMITTED DISEASES (STDs)
SL.
NO.
STD
CAUSAL
AGENT
1
CHLAMYDIOSIS
Chlamydia
trachomatis
2
GONORRHOEA
Nisseria
gonorrhea
3
TRICHOMONIASIS
Tricomonas
vaginalis
4
GENITAL HERPES
Herpes
simplex virus
5
SYPHILIS
Trepanema
pallidum
6
GENITAL WART
7
HEPATITIS-B
Human
papilloma
virus
Hepatitis –B
virus
8
AIDS
HIV
SYMPTOMS
EFFECT ON
FOETUS
EFFECT ON PERSON
AFFECTED
Painful urination
& intercourse
Mucus
discharge from
penis/vagina
Painful urination
in men
Premature
birth,blindness,
Pneumonia
Pelvic inflammatory
disease,
Infertility,Ectopic
pregnancy
Still birth,
Blindness
Inflammation,
Itching& vaginal
white discharge
(Leucorrhoea)
Genital sores,
Fever
Not known
Pelvic inflammatory
disease,
Infertility,Rash,Death
Valvar erythema,
Burning dysuria
Still birth, Brain
damage
Cervical cancer.
Initially sores in
genitalia &
mouth,
Rashes
Warts on
genitalia
Premature birth,
Miscarriage, Still
birth
Death
Not known
Cervical cancer
Fatigue, Fever,
Jaundice, Rash,
Abdominal pain
Low birth weight
Liver cirrhosis, Liver
cancer
Fever, Prone to
infection,
Inflammation
AIDS affected
Dementia, Death
IMPORTANT NOTES
• Indian population is identified as ‘Young population’ whereas population of USA, England
,Germany etc. are identified as ‘Ageing population’.
• In India, Kerala has lowest Birth rate & U.P. highest.
• Deficiency of Manganese causes infertility & Vitamin E is considered as Antisterility Vitamin.
IMPORTANT TERMS TO REMEMBER
AMNIOCENTESIS: Foetal test based on chromosomal pattern in amniotic fluid surrounding the
developing embryo. can be used for sex determination.
LACTATIONAL AMENORIA: Absence of menstruation due to disruption of ovulation during the period
of intense lactation following parturition.
INTRA UTERINE DEVICES(IUDs): A medical device of insertion of artificial barrier in the uterus
through vagina for obstructing sperm entry.
STERILISATION: Surgical intervention for stopping pregnancy by blocking gamete transport pathway
in male/female.
ASSISTED REPRODUCTIVE TECHNOLOGIES(ART): Artificial technological devices to enable
couples to have children when fail they to get child due to any reproductive disorder.
ARTIFICIAL INSEMINATION: Medical technological devices by which semen collected from a healthy
donor is artificially introduced into the vagina or uterus of female.
ETIOLOGY:Study of causes of diseases.
EPIDEMIOLOGY:Mode of transmission of diseases.
RECANALISATION: Attachment of cut Vasa deferentia with plastic tubes during Vasectomy.
CASTRATION: Surgical removal of Testes.
POPULATION CRASH: Rapid decline in the population.
POPULATION EXPLOSION: Rapid increase in the population.
AGE COMPOSITION: Relative abundance of the organisms of different ages in the population.
IN-VITRO FERTILISATION: Artificial technique of fusion of gametes outside the body in laboratory
condition, in almost similar conditions as that of the body.
INFERTILITY: Inability of a couple to produce children in spite of unprotected sexual cohabitation.
Questions.
Q1) Table of certain terms associated with ART. Fill in the spaces a,b,c,d.(1X4 )
IVF&ET
a
b
Introduction of zygote/embryo with 8 blastomeres into fallopian tube.
c
Introduction of ova of a donor into the fallopian tube
d
Introduction of semen from the husband or healthy donor into the uterus.
Q3)Why is the term test tube baby a misnomer.(3)
Baby not developed in test tube. Only fertilization carried out in test tube in lab conditions. The fertile
egg is then transferred into the fallopian tube or uterus where it develops and grows into a normal baby
is born.
Q4. Why do intensely lactating mothers do not generally conceive?
Due to suppression of gonadotropins’
Q5 Name 2 sexually transmitted diseases caused by bacteria.
Syphilis and gonorrhea.
Chapter 5 : Genetics
Relationship between genes and chromosome of diploid organism and the terms used to describe them
Know the terms
Terms
Meaning
Example
Locus
Address/ location of a gene in a chromosome
T,A.b,d etc
Allele
Allelomorphs= alternative form of a gene
T and t OR A and a etc
Homozygous
Both alleles of a gene at a locus similar
AA or aa
Mendel's first law ( Law of dominance )characters are controlled by discrete units called genes (allele)
which occur in pair. In heterozygous condition only one gene that is dominant can express itself. (Can
be explained by monohybrid cross)
Mendel's second law (Law of segregation): The two alleles received, one from each parent,
segregate independently in gamete formation, so that each gamete receives one or the other with equal
probability. (Can be explained by monohybrid cross)
Mendel's third law (Law of recombination): Two characters determined by two unlinked genes are
recombined at random in gamete formation, so that they segregate independently of each other, each
according to the first law (note that recombination here is not used to mean crossing-over in meiosis).
(Can be explained by dihybrid cross)
This is what Mendel said (summary) :
1) Dominant alleles overpower recessive alleles. Dominant traits overpower recessive traits.
2) Rule of segregation (Separation): Gametes (sex cells) only receive one allele from the original
gene.
3) Rule of Independent assortment: One trait will not determine the random selection of another.
Incomplete dominance: When one allele of a gene is not completely dominant over the other and the
F1 hybrids are intermediate between two parents. The phenotypic and genotypic ratio is same.1:2:1 in
F2 generation. E.g. Snapdragon or Antirrhinum majus
Co dominance: Two alleles of a gene are equally expressive and dominant in a generation eg. Human
blood group
( Note : Human blood group is also an example for multiple allelisim i.e when a gene exists in more
than two allelic forms)
Basic outline of Mendels cross
1. Pure breeding parents for a pair of contrasting character (allelic pair) is taken
Eg.Tall pure-bred pea plants (TT) & short pure-bred pea plants (tt)
2. Gamete formation (Meiosis)
3. Hybridization (crossing is done)
4. F1 generation - the product of the above cross (are called hybrids)
Linkage
Tendency of genes on same chromosome to remain together
Such genes are called – linked genes.
Linked genes present only parental types
Figure Schematic of Genetic Linkage and Recombination
(A) Two homologous chromosomes: blue (paternal) and orange (maternal). Three genes with
separate alleles and linkage " noted (A,a; B,b; C,c;).
(B) Crossing over during meiosis (chiasma formation)
Cross
Result of F2 generation
Monohybrid Tt X Tt
Dihybrid cross
YyRr X YyRr
Incomplete dominance
Rr X Rr
Phenotypic ratio
3:1
9:3:3:1
Genotypic ratio
1:2:1
1:2:1:2:4:2:1:2:1
1:2:1
1:2:1
Co Dominance and multiple allelisim
Blood group
Possible genotype
A
IAIA OR IAi
B
IBIB OR IBi
AB
IAIB
O
ii
Crosses of blood group (CO DOMINANCE)
Blood group
Possible genotype
AXA
IAIA X IAIA
IAIA X IAi
IAi X IAi
BXB
IBIB X IBIB
IBIB X IBi
IBi X IBi
AB X AB
IAIB XIAIB
OXO
ii X ii
Possible phenotype
A
A
A;O
B
B
B; O
AB: A; B
O
POSSIBLE BLOOD GROUP OF PROGENY WITH RESPECT TO THE BLOOD GROUP OF
PARENTS
Parent
AXA
AXO
AXB
Progeny
A
+
+
+
B
+
AB
+
O
+
+
+
Sex determination and sex chromosome
Organism
Male
Human beings
XY
Birds
ZZ
Insects
XO
Female
XX
ZW
XX
Pedigree Analysis
Pedigree is a chart of graphic representation of record of inheritance of a trait through several
generations in a family
Symbols used:- refer NCERT Text Book
Four patterns of inheritance
AUTOSOMAL DOMINANT
1. Traits are controlled by dominant genes
2. Both males and females are equally affected
3. traits do not skip generations
4. e.g. polydactyly, tongue rolling ability etc
AUTOSOMAL RECESSIVE
1. Traits controlled by recessive genes and
appear only when homozygous
2. Both male and female equally affected
3. Traits may skip generations
4. 3:1ratio between normal and affected.
5. Appearance of affected children from
normal parents (heterozygous)
6. All children of affected parents are also
affected.
7. e.g.- Albinism, sickle cell anaemia etc
Now try to answer
1. Is it possible that this pedigree is for an autosomal dominant trait?
2.
Can two individuals that have an autosomal dominant trait have unaffected children?
3.
Is it possible that this pedigree is for an autosomal dominant trait?
4.
Is it possible that this pedigree is for an autosomal dominant trait?
5.
6.
Is it possible that the pedigree above is for an autosomal recessive trait?
Assuming that the trait is recessive, write the genotype of each individual next to the symbol
7.
8.
Is it possible that the pedigree above is for an autosomal recessive trait?
Write the genotype of each individual next to the symbol
9.
Is it possible that the pedigree above is for an autosomal recessive trait?
A = normal
a = the trait (a genetic disease or abnormality)
10. Is it possible that the pedigree above is for an X-linked recessive trait?
11. Write the genotype next to the symbol for each person in the pedigree
16. Is it possible that the pedigree above is for an X-linked recessive trait?
Clues
Autosomal Recessive
Affected
AA
Aa
aa
X- chromosome linked
recessive
X− X−
X− Y
Autosomal Dominant
Unaffected
aa
AA
Aa
XX
X X−
XY
TERMINOLOGIES
Allele = A factor or letter that makes up a gene. 2 alleles make up one gene. Alternative forms of a
genetic locus; a single allele for each locus is inherited separately from each parent (eg., at a locus for
eye color the allele might result in blue or brown eyes).
Alleles = "B" and "b" are different alleles.
Autosomal = refers to genes that are not found on the sex chromosomes.Autosomal chromosomes are
ones that are not XX and XY. A chromosome not involved in sex determination. The diploid human
genome consists of 46 chromosomes, 22 pairs of autosomes, and 1 pair of sex chromosomes (the X
and Y chromosomes).
Carrier = a person who has a defective gene and a dominant normal gene and therefore, is normal.
(Nn)
Centimorgan (cM): A unit of measure of recombination frequency. One centimorgan is equal to a 1%
chance that a marker at one genetic locus will be separated from a marker at a second locus due to
crossing over in a single generation. In human beings, 1 centimorgan is equivalent, on average, to 1
million base pairs
Chromosomes = 46 are found in human cells. Genes are carried among chromosomes.
Clones: A group of cells derived from a single ancestor.
Cystic Fibrosis = Autosomal recessive. Mucous in lungs.Death in the 20’s.
Dominance = This is one of Johann Gregor Mendel’s principles. In his studies with pea plants Mendel
notices that pure tall plants bred to pure short plants resulted in tall hybrid plants. Tallness was
dominant over shortness.
Dominant = an allele that overpowers another is dominant.
Down's Syndrome = due to an extra chromosome in (21st pair).
Gamete = sperm or egg. Germ Cell. In humans, germ cell contains 23 chromosomes.
Genetics: The study of the patterns of inheritance of specific traits
Gene = Every trait is controlled by a gene. A human has 20,000 genes. Genes are controlled by 2
Homozygous = alleles of a gene are "the same"
Homologous chromosomes: A pair of chromosomes containing the same linear gene sequences,
each derived from one parent
Huntington's Chorea = Autosomal Dominant. People die at 40 +... Jerky muscular motions
Hybrid = alleles of a gene are "different" (Hh). See heterozygous.
Independent Assortment: Johann Gregor Mendel’s 2nd principle. States that alleles of one gene
separate independently from alleles of another gene. In other words, eye color does not affect a
person’s ability to roll his or her tongue.
In vitro: outside a living organism.
Karyotype: Photomicrograph of an individualschromosomes arranged in a standard format showing
the number, size, and shape of each chromosome type.
Linkage: Proximity of two or more genes on a chromosome.The closer together the genes, the lower
the probability that they will be separated during meiosis and hence the greater the probability that they
will be inherited together.
Linkage map: relative positions of genetic loci on a chromosome, determined on the basis of how often
the loci are inherited together. Distance is measured in centimorgans (cM).
Locus (pl. loci): The position on a chromosome of a gene or other chromosome marker; also, the DNA
at that position. The use of locus is sometimes restricted to mean regions of DNA that are expressed.
Meiosis: kind of cell division that produces sperm and egg. Meiosis cuts the number of chromosomes
in half. In humans, for instance, the nuclei of body cells contain 46 chromosomes. Due to meiosis, sex
cells carry only 23 chromosomes – one chromosome from each original homologous pair.
Mendel, Johann Gregor = The father of genetics (said that traits are controlled by 2 factors etc...)
Mutation = Change in the DNA instructions. Change in DNA sequence. Change can be beneficial,
detrimental or neutral. Ultimately results in change in protein. For instance, random genetic mutation
gave rise to the dark phenotype of the peppered moth.
Non-Disjunction: When homologous chromosomes fail to segregate properly during meiosis. Down
syndrome, Turner syndrome and Klinefelter syndrome result from non-disjunction.
Phenotype : the way an organism looks.( EXTERNAL CHARACTERISTICS)
Recessive : A small, weaker allele is recessive. (CANNOT EXPRESS ITSELF IN HETEROZYGOUS
CONDITION)
Segregation : One of Mendel’s principles. Mendel said all genes are comprised of 2 factors, one from
each parent. Chromosomes segregate during meiosis. These factors (alleles) of a gene separate during
the formation of gametes (sperm and egg). This ensures that each parent contributes 50% of their
genetic information.
Sex chromosomes : chromosomes that determine sex (XY and XX)
Somatic Cell : Body cell that contains 46 chromosomes in humans.
Tay Sachs : Autosomal recessive. Children die young. Head enlarges....
Trait : feature of an organism.
Questions
1 Mark Questions
Q1. Mendel’s work was rediscovered by three scientists independently. Name any two of them.
Q2. How do we predict the frequency of crossing over between any two linked genes ?
Q3. Why did Mendel select pea plant for his experiment?
Q4. In a monohybrid cross the genotypic and phenotypic ratio is 1:2:1. What type of Inheritance is it
example of? Give one example.
Q5. If a human zygote has XXY sex chromosomes along with 22 pairs of autosomes. What sex will the
individual be? Name the syndrome.
Q6. Which of the following is a dominant & recessive trait in garden peatall stem, constricted pod.
2 Mark Questions
Q7. A mother with blood group ‘B’ has a fetus with blood group ‘A’ father is ‘A’. Explain the situations?
Q8. The genes for hemophilia are located on sex chromosome of humans. It is normally impossible for
a hemophilic father to pass the gene to his son. Why?
Q9. Justify the situation that in human beings sex of the child is determined by father and not by
mother?
Q10. What is trisomy? Give one example.
11)Differentiate between Genotype and Phenotype ( 2) 1 2 Genotype Total genetic constitution of an Individual Individuals with different genotype may produce the same phenotype. Phenotype External appearance of an individual. Individuals with different phenotypes always have different genotypes. 12)Distinguish between Complete and Incomplete linkage. (2) 1 Complete Linkage No crossing over between the genes 2 Linked genes show no recombination 3 Marks Questions
Incomplete linkage Crossing over at the time of gamete formation Recombination Progeny is produced in addition to parental type. 5 Marks Questions
Q16. A dihybrid heterozygous round, yellow seeded garden pea was crossed with a double recessive
plant.
(i)
What type of cross is this ?
(ii)
Work out the genotype & phenotype of the progeny.
(iii)
What principle of Mendel is illustrated by it ?
Ans16. Test Cross
(1)
Working out
(3)
Principle of segregation
(1)
Q17. Describe the nature of inheritance of the ABO blood group in humans. In which ways does this
inheritance differ from that of height of the plant in garden pea?
Ans17. Refer Pg 77 NCERT Book
(3)
Dominance & multiple allelism where as height shows dominance
(2)
Chapter 6. MOLECULAR BASIS OF INHERITANCE
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DNA largest macromolecule made of helically twisted, two, antiparallel
polydeoxyribonucleotide chains held together by hydrogen bonds.
X-ray diffraction pattern of DNA by Rosalind Franklin showed DNA a helix.
Components of DNA are (i) deoxyribose sugar, (ii) a phosphate, and (iii) nitrogen containing
organic bases.
DNA contains four different bases called adenine (A), guanine (G) cytosine (C), and thymine (T).
These are grouped into two classes on the basis of their chemical structure: (i) Purines (with a
double ring structure) and (ii) Pyrimidines (with a single ring structure)
1953.James Watson and Francis Crick proposed three dimensional structure of DNA and won the
Nobel prize.
DNA double helix with sugar phosphate back bone on outside and paired bases inside.
Planes of the bases perpendicular to helix axis.
Each turn has ten base pairs.( 34 A0)
Diameter of helix 20 A0.
Two strands of DNA antiparallel.
DNA found both in nucleus and cytoplasm.
Extranuclear DNA found in mitochondria and chloroplasts.
Two chains complementary
Two chains held together by hydrogen bond.
Adenine-Thymine pair has two hydrogen bonds.
Guanine-Cytosine pair has three hydrogen bonds.
Upon heating at temperature above 80-90 degree two strands uncoil and separate (Denaturation)
On cooling two strands join together (renaturation /annealing)
DNA is mostly right handed and B form.
Bacterial nucleoid consists of a single circular DNA molecule .
# DNA of eukaryotes is wrapped around positively charged histone proteins to form nucleosome.
# Nucleosome contains 200 base pairs of DNA helix.
# Histone octamer =2(H2a+H2b+H3+H4)
# Linker DNA bears H1 protein
# Chromatin fibres formed by repeated units of nucleosomes.
# Non histone proteins required for packaging.
# Regions of chromatin, loosely packed and stains lightly called euchromatin.
# Regions of chromatin, densely packed and stains darkly is called heterochromatin.
DNA AS THE GENETIC MATERIAL
Transformation experiment or Griffith effect.
•
Griffith performed his experiments on Mice using Diplococcus pneumoniae.
•
Two strains of bacteria are S-type and R-type cells.
•
Experiments
Living S-strain Injected into mice →Mice killed
Living R-strain Injected into mice → Mice lived
Heat Killed S-strain Injected into mice →Mice lived
Living R-strain + Heat Killed S-strain Injected into mice→Mice killed
# Griffith concluded that R type bacteria is transformed into virulent form.
# Transformation - change in the genetic constitution of an organism by picking up genes present in the
remains of its relatives.
BIOCHEMICAL CHARACTERISATION OF TRANSFORMING PRINCIPLE
# Proved by Oswarld Avery, Colin Macleod, Maclyn Mc Carty
From this we conclude that DNA is the genetic material.
Semi conservative nature of DNA Mathew Messelson and Franklin start.
E.coli
Grown on 15 NH4Cl culture medium Both strands of DNA have 15N (N15 N 15)
Shifted to 14NH4Cl culture medium After
DNA extracted subjected to CSCl density gradient centrifugations 20 min.
After
40 min.
Hybrid/ Intermediate type of DNA (N15 N14) Equal amount of light DNA (N15 N14) and hybrid DNA (N15 N14) 8. 3 Replication of DNA In Eukaryotes:
Definition: "Process by which DNA produces daughter DNA molecules which are exact copies of the original
DNA." In eukaryotes, DNA is double stranded. The two strands are complementary to each other because of
their base sequences.
Semi-conservative method of DNA replication Important points:
The various steps involved in this process are summarized as follows:
i. Mechanism of replication starts at a specific point of the DNA molecule, called origin.
ii. At origin, DNA strand breaks because of an incision (nick). This is made by an enzyme called incision
enzyme (endonuclease).
iii. The hydrogen bonds joining the two strands are broken by the enzyme.
iv. The two strands start unwinding. This takes place with the help of a DNA unwinding enzyme Helicases.
Two polynucleotide strands are thus separated.
v. The point where the two strands separate appears like a fork or a Y-shape. This is described as a replicating
fork.
vi. A new strand is constructed on each old strand. This takes place with the help of a small RNA primer
molecule which is complimentary to the DNA at that point.
vii. Each old DNA strand acts as a template (site) for the construction of new strand. The RNA primer attaches
itself to the old strand and attracts the enzymes (DNA polymerase III) which add new nucleotides through base
complementation. The deoxyribose nucleotides are present in the surrounding nucleoplasm. New DNA strand
is thus constructed opposite to each old strand.
viii. Formation of new complementary strand always begins at the 3' end of the template strand (original strand)
and progresses towards the 5' end (ie in 3' - 5' direction). Since the new strand is antiparallel to the template
strand, it is obvious that the new strand itself is always developed in the, 5'-3' direction. For this reason when the
two original strands separate (then with respect to the origin of separation), one acts as 3'-5' template while the
other acts as 5'- 3' template.
ix. Of the two, the replication of 3'-5' template begins first. Hence the new strand formed on it is called the
leading strand. The other template (5'-3') must begin replication at the fork and progress back toward the
previously transcribed fragment. The new strand formed on it is called the lagging strand.
x. Replication of the lagging strand takes place in small fragments called Okazaki fragments. These are then
connected together by the enzyme ligase.
xi. Replication may take place in only one direction on the DNA helix (unidirectional) or in two directions
(bidirectional).
xii. At the end of the process, two double stranded DNA molecules are formed from the original DNA molecule.
Three major types of RNA:
1.
Messenger RNA or mRNA- has the information to make
a protein. It is very unstable and comprises ~5% of total RNA polymer. Its length is highly variable,
of the range 7503000 nucleotides.
Transcription in Prokaryotes
Promoter+
RNA polymerase Co ding Strand With Sigma factor Template Strand Ribonucleotide
With the help of rho factor
Terminator RNA Transcription in Eukaryotes
RNA Polymerase
DNA template strand
Primary transcripts (Exon + Intron)
Splicing Introns removed Exons joined (hn RNA) Capping at 5’ end Tailing at 3’ end (200‐300 Adenylate residue)
GENETIC CODE
Initiation Codon AUG
commaless Triplet Universal Non ambigious Genetic Code Degenerate Non overlapping Linear Nonsense codon (UAA,UAG,UGA)
Non ambiguous—Particular codon will always code for same amino acid.
Degenerate—Number of codons can code for one amino acid.
Universal—Specific codon codes for same amino acid in all organisms.
Translation:™ Process of joining of amino acids by peptide bond to form a polypeptide.
1. Activation of amino acids • AA+ATP+E Mg+2AA‐AMP‐E+ PPi • AA‐AMP‐E+tRNA ÆAA‐tRNA+AMP+E 2. Initiation •
•
•
Small subunit (40s) of ribosome binds with mRNA. Charged t RNA specific for initiation codon reaches P site Larger subunit (60s) of ribosome now combines with 40s‐m RNA—t RNA met complex in the presence of Mg+2 3. Elongation •
•
•
Second t‐RNA charged with amino acid occupies A site of ribosome. Peptide bond formation between methionine and second amino acids with the help of enzyme peptide transferase. Ribosomes moves over m RNA in 5’Æ3’ 4. Terminator •
•
•
Translation stops when non sense codons (Stop codons) reached. No t RNA for stop codons (UAA,UAG,UGA) Synthesized polypeptide is released with the help of release factor. Refer to figure number 6.14 of page 117 of text Book
SWITCH OFF CONDITION
i‐gene Repressor Protein + Operator gene RNA polymerase can not access the structural gene due to repressor –operator complex (ROC) No transcription of the structural gene
No enzyme or protein formation SWITCH ON CONDITION
i‐gene
Repressor Protein+ Inducer (Lactose) Repressor Inducer complex (RIC) Structural gene accessed by RNA polymerase (no blockage at operator)
Methodologies of Human Genome Project
Sequence annotation (Sequence the whole set of genome) ‐Isolation of total DNA from the cell ‐Fragmentation by restriction endonuclease Fragments cloned in suitable host BAC/YAC Fragments sequenced using automated DNA sequences. Sequences arranged on the basis of overlapping regions. Expressed sequence Tags (EST) (Identifying all the genes Expressed as RNA) Functions of 50% discoursed genes unknown
Repetitive sequences contribute large portion 3164.7 millions Nucleotides Average gene consists of 3000 bases Salient features of Human Genome Total genes 30,000 <2% gene codes protein Largest gene dystrophic Y chromosome has 231 genes Chromosome‐1 has 2968 gene
Application of Human genome project
-: Identification of defective genes.
-: Opportunity to offer early treatment.
-: Identification of genes that confer susceptibility to certain disease.
-: Prediction of protein that the genes produce.
-: Drug designing to enhance or inhibit the activities of the proteins.
TECHNIQUE FOR DNA FINGER PRINTING
™ Technique developed by Dr.Alec Jeffreys.
™ Process is also known as DNA typing/DNA profiling.
DNA extraction from the cells in high speed refrigerated centrifuge
Amplification of DNA content by PCR (Polymerase chain reactions)
DNA fragmentation by Restriction endonuclease
Dark band develops at probe site
*Probes/ Markers are radioactive synthetic DNA complementary to VNTR
QUESTIONS
ONE MARK QUESTION
1.Name the genetic material in TMV.
2.Write the scientific name of the plant on which Taylor et al performed their experiment.
3.What would be the proportion of light and hybrid density DNA molecules after 80 minutes of a single
cell of E. coli growth?
4.When does DNA replicate in the cell cycle ?
5.Name the amino acids having only one codon.
TWO MARK QUESTION
1.What is meant by semiconservative nature of DNA replication?
2. What are the functions of DNA polymerase?
3. What is frame shift mutation ? Name the type of mutation that does not affect protein synthesis .
4.What are the untranslated regions (UTRs) ?
5.Briefly describe polymorphism.
6. What do you mean by phosphodiester bond?
Ans: The bond which is formed between the 3’-OH of one deoxyribonucleotide and 5’-phosphate
residue of an adjacent deoxyribonucleotide.
7. What type of transcription is found in retrovirus? Name the enzyme.
Ans: in retrovirus the genetic information flows from RNA to DNA and is called reverse transcription
while the enzyme involved is called reverse transcriptase.
8. What would happen if histones were to be mutated and made rich in amino acids aspartic acid and
glutamic acid in place of basic amino acids such as lysine and arginine?
10. Comment on the utility of variability in number of tandem repeats during DNA fingerprinting.
Ans: Tandemness in repeats provides many copies of the sequence for fingerprinting and variability in
nitrogen base sequence in them. Being individual-specific, this proves to be useful in the process of
DNA fingerprinting.
11. Why is lactose considered an inducer in lac operon?
Ans: Lactose binds to repressor molecule and prevents it from binding with the operator, as a result
RNA polymerase binds to promoter-operator region to transcribe the structural genes. Thus the lac
operon is switched on.
12. If a double-stranded DNA has 20 % of cytosine, calculate the % of adenine in the DNA.
Ans: cytosine = 20%, therefore guanine = 20%
According to Chargaff’s rule,
A+T = 100 – (G+C)
A+T = 100 – 40. Since both adenine and thymine are in equal amount.
Therefore, Thymine= Adenine = 60%/2 = 30%
13. What is cistron?
Ans: Region of the DNA template (gene) coding for a single protein is called cistron.
THREE MARK QUESTIONS
1.Describe the discontinuous synthesis of DNA.
2. How is Lac operon “switched on” in an E.coli cell ?
3.Name the three RNA Polymerases found in eukaryotes and mention their functions.
4.Explain the two major approaches involved in the sequencing of genomes.
FIVE MARKS QUESTIONS
1.Describe the salient features of the double helical model of DNA.
2 Bring out the salient features of genetic code
6. What are the differences between DNA and RNA?
Ans:
DNA
RNA
1. Polymer
of
deoxyribonucleotides
consisting of two antiparallel strands.
2. Purine nucleotides are- adenine and
guanine. Pyrimidine nucleotides are
cytosine and thymine.
3. Main function is to carry all the hereditary
characteristics.
4. Mainly present in nuclear material of
chromatin fibre, mitochondria and
chloroplast.
7. What are B-DNA, A-DNA and Z-DNA?
Ans:
B-DNA
1. Most predominant form
1.
of DNA, the
conformation described
by Watson and Crick,
present under
physiological conditions
in the body, right
handed double helix.
2.
2. Base pair per turn 10.
3.
3. Diameter 2 nm.
1. Polymer of ribonucleotides consisting of
only a single strand.
2. Purine nucleotides are- adenine and
guanine. Pyrimidine nucleotides are
cytosine and uracil.
3. Main function is to perform protein
synthesis.
4. Mainly present in cytoplasm, nucleolus
and chromosome.
A-DNA
In lower concentration
of salts or in a partially
dehydrated state, this
form is present, found
in some Gram positive
bacteria, right handed
double helix.
Base pair per turn 11.
Diameter 2.6 nm.
Z-DNA
1. It has been discovered
in synthetically made
oligodeoxynucleotides,
left handed double helix.
2. Base pair per turn 12.
3. Diameter 1.8 nm.
8. What do you mean by grooves of DNA?
Ans: DNA backbone is somewhat tilted from its vertical axis, it has two uneven grooves or furrowings
i.e., one major groove (about 12 A˚) and one minor groove (about 6 A˚). They are the protein binding
sites of DNA.
11. What are the differences between euchromatin and heterochromatin?
Ans:
euchromatin
heterochromatin
1. During interphase certain areas in
1. During interphase certain areas in
chromatin are loosely coiled and stain
chromatin remain tightly coiled or
less intensely.
condensed and hence stain darkly.
2. These contain the genes or the coding
2. These contain non-coding DNA like the
DNA.
repetitive DNA.
CHAPTER-7: EVOLUTION
Evolution: Process that results in heritable changes in a population spread over many generations
(change in allele frequencies over time) leading to diversity of organisms on earth. It is the genetic
change in a population or species over generations (Genes mutate, individuals are selected, and
populations evolve).
Evidences of evolution:
From comparative anatomy: Comparison of body structures amongst different species comes under
comparative anatomy. Certain anatomical similarities among species bear witness to evolutionary
history. eg. the same skeletal elements make up the forelimbs of man, horse, whale and bat, but each
of them perform different functions. However, structural similarities in all mammals descended from a
common ancestory with prototype forelimbs are common suggesting homology. Comparative anatomy
confirms that evolution is a remodeling process. Ancestral structures that originally functioned in one
capacity become modified as they take on new functions-‘descent with modification’.
Adaptive radiation or mega evolution: Diversification, over evolutionary time, of a species or group of
species into several different species or subspecies that are typically adapted to different ecological
Group of organisms diversify greatly and take on new ecological roles. (for example, Darwin's finches
in the Galapagos Island and Marsupials in Australia).
Allopatric speciation:or geographic speciation is speciation that occurs when biological populations
of the same species become vicariant or permutable— isolated from each other to an extent that
prevents or interferes with genetic interchange. Can be the result of population dispersal leading
to emigration, or by geographical changes such as mountain formation, islandformation, or large scale
human activities (for example agricultural and civil engineering developments).
Artificial selection: Process by which humans breed animals and cultivate crops to ensure that future
generations have specific desirable characteristics.(In artificial selection, breeders select the most
desirable variants in a plant or animal population and selectively breed them with other desirable
individuals).
Atavism or reversion: the reappearance of those ancestral characteristics in an organism or in the
organisms of a group, which do not occur normally or which represent the reminiscent of normal
structures possessed by the individuals of other groups. Examples - human baby born with tail etc.
Big bang theory: States that the universe began in a state of compression to infinite density, and that
in one instant all matter and energy began expanding and have continued expanding ever since.
Biological Evolution:
Convergent Evolution: Convergent evolution takes place when species of different ancestry begin to
share analogous traits because of a shared environment or other selection pressure. For example,
whales and fish have some similar characteristics since both had to evolve methods of moving through
the same medium: water.
Darwin’s finches: Divergent Evolution: Evolutionary pattern in which two species gradually become
increasingly different. This type of evolution often occurs when closely related species diversify to new
habitats. On a large scale, divergent evolution is responsible for the creation of the current diversity of
life on earth from the first living cells. On a smaller scale, it is responsible for the evolution of humans
and apes from a common primate ancestor. Adaptive radiation is one example of divergent
evolution.
Directional selection shifts the overall makeup of the population by favoring variants of one extreme
within a population. Natural selection may be directional: it may favor, for example, smaller individuals
and will, if the character is inherited, produce a decrease in average body size. Directional selection
could, of course, also produce an evolutionary increase in body size if larger individuals had higher
fitness.
Disruptive selection, like directional selection, favors the variants of opposite extremes over
intermediate individuals. Disruptive selection differs in that sudden changes in the environment creates
a sudden force favoring that. In nature, sexual dimorphism is probably a common example.
Founder Effect: A cause of genetic drift attributable to colonization by a limited number of individuals
from a parent population. When few individuals colonize a new habitat, genetic drift will more than likely
occur.
The founder population is small and again the alleles present in this small population will not be
representative of the original population. Saltation (from Latin, saltus, "leap") is a sudden change from
one generation to the next, that is large, or very large, in comparison with the usual variation of an
organism. The term is used for occasionally hypothesized, non gradual changes (especially single-step
speciation) that are atypical of, or violate, standard concepts involved in neo-Darwinian evolution.
Genetic drift: Changes in the frequencies of alleles in a population that occur by chance, rather than
because of natural selection.
Gene flow: movement of genes into or through a population by interbreeding or by migration.
Gene frequency: The frequency in the population of a particular gene relative to other genes at its
locus.
Expressed as a proportion (between 0 and 1) or percentage (between 0 and 100 percent).
Gene pool: All the genes in a population at a particular time.
p2 + 2pq + q2 = 1 or, (p + q)2 = 1
Calculation of allele frequencies
Recessive traits: If the frequency of a recessive trait such as cystic fibrosis or PKU is known, it is
possible to calculate allele frequencies and genotype frequencies using the Hardy Weinberg equation
and its assumptions are as follows:
i. say 1 in 1, 2500 Indian newborns have cystic fibrosis which means that the frequency of
homozygotes for this recessive trait is
q² = 1/2,500 = 0.0004
ii. The square root of the frequency of recessives is equal to the allele frequency of the cystic
fibrosis allele
q = (0.0004)0.5 = 0.02
iii. The frequency of the normal allele is equal to 1 - the frequency of the cystic fibrosis allele
p = 1- q = 1 - 0.02 = 0.98105
iv. The frequency of carriers (heterozygotes) for the cystic fibrosis allele is
2pq = 2 (0.98)(0.02) = 0.04 or 1/25
v. The frequency of homozygotes for the normal allele is
p² = (0.98)² = 0.96vi.
Thus the population is composed of three genotypes at the calculated frequencies of homozygous
normal = 0.96, heterozygous carriers = 0.04, homozygous affected = 0.0004
Macroevolution: large scale evolutionary changes, occurring over a long period of time and involving
the origin of major taxa. Example: extinction of Dinosaurs.
Mimicry: Superficial but close resemblance of one organism to another or to natural objects among
which it lives, that secures its concealment, protection or some other advantage so that it either
escapes itself from observation or advertises as being harmful, which is not actually the case. The
organism which mimics is known as mimic or mimetic and the organism or object which is imitated or
copied is called the model.
The palatable viceroy butterfly, Lementis, which can be easily preyed upon, mimics the distasteful or a
non-palatable monarch butterfly, Danais.
Polymorphism: the existence of two or more forms or morphs of the same species within the same
population at the same time and place. The differences in such forms may be morphological,
physiological or biochemical and are genetically determined.
Balanced polymorphism
1. Individuals with two or more forms coexist in
the same population of a species in stable
environment and show almost constant ratio.
2. In a population showing balanced
polymorphism, the genotypic frequencies of
various forms occur at equilibrium.
3. Example: people heterozygous (HbA/HbS) for
the trait of sickle cell anemia are resistant to
malarial infection in malarial prone region like
Eastern Africa.
In normal human population natural selection
tends to eliminate gene HbS from the
population. But it has been found that the
frequency of gene HbS is usually high in
areas prone to malaria in East Africa where it
is usually high due to selective advantage of
heterozygotes
resulting
in
stable
polymorphism for gene HbS.
Transient polymorphism
1. Populations undergoing a strong selection
pressure and one form or morph is being
strongly favoured while the other is getting
eliminated. Thus this polymorphism lasts for
a short period coz it lasts till the
disadvantageous form gets eliminated
completely or is reduced to a low frequency.
2. In a population showing transient
polymorphism, the different frequencies
occur at different ratio.
3. Example: see ‘industrial melanism’.
Thus polymorphism in peppered moth was
only for a short period and favoured strong
selection. The transient polymorphism is
seen during directional selection, where one
form or character is gradually being replaced
by another.
Phylogeny: evolutionary history of a particular taxonomic group.
Stabilizing selection favors the norm, the common, average traits in a population .In nature, natural
selection is most commonly stabilizing. The average members of the population, with intermediate body
sizes, have higher fitness than the extremes. Stabilizing selection culls extreme variants from the
populations.
Sympatric speciation: origin of new species from populations of a single species which have been
genetically isolated because of physiological or behavioural incompatibility.
Vestigial organs: functionless homologous organs that have no apparent function in certain organism.
(supposed to be remnants of organs that had been well developed and functional in their ancestral
Time period
10-15 Mya
Name
Dryopithecus (ape like)
Brain capacity
Ramapithecus (man like)
2 mya
1.2 mya
100,000-40,000
mya
25000mya
Australopithecines ( cave dwellers)
Homo habilis
Homo erectus
500cc
700cc
800cc to 1300cc
Neanderthal man
1450cc
Homo sapiens
1650cc
Remarks
East Africa, Asia; closely related
to chimpanzee
Shivalik Hills; erect posture,
small canine
African Ape Man ; height 1.5mts
Tool Maker, Community Life
Knew how to use fire, larger
teeth
East and central Asia
Modern man ; height1.5 to 1.8
mts; flat face
Synopsis of Human evolution Major Events during Geological Periods (Time scale):
PERIOD
Precambrian:
Cambrian
Ordovician
Silurian
Devonian
Carboniferous
diversity of insects, first reptiles appear.
Permian
Triassic
Jurassic
Cretaceous
Tertiary
EVENTS
Origin of life, Oxygen evolution through photosynthesis
Flourishing of the invertebrates, increase in algal diversity,
appearance of vertebrates.
Plants begin to colonize land.
Increase in diversity of fish.
Amphibians appear
Extensive forest, dominance of amphibians, increase in
Age of reptiles begin
Dinosaurs evolve and spread, first mammal appear
First bird and first flowering plant appear.
Dominance of flowering plants.
Age of mammals begin
Organic Evolution Study Questions
1. Biological evolution is the cumulative changes that occur in a
____________________ over time.
2. The principle source of change (genetic variation) is due to this type of
chromosomal event. _____________________
3. Charles Darwin published his landmark book entitled
________________________________________ in 1859.
4. In his book, Darwin states that the origin of all life forms is due to random
._______________
5. Darwin premise that all humans, animals, and bacteria share a common distant
ancestor is explained with the concept of __________________ with
._________________________
6. Similarities of the structures between dissimilar species (ex: arm bones) are
called ________________ structures.
7. Darwinian Theory tells us that
_________________ + ________________ = new species
8. Neo-Darwinian Theory tells us that beneficial genetic mutations concentrated in a
population over time can result in the formation of new ____________________.
9. List three characteristics that always provide a selective advantage.
Evolution Study Questions KEY
1. Population.
2. Mutation
3. “The Origin of Species”
4. Chance.
5. Descent modification.
6. Homologous.
7. Mutability + natural selection = new species
8. Species.
9. i. self-defense ii. reproductive success iii. food gathering ability
Probable questions:
Short Answer Questions
3. What are vestigial organs? How do they support the organic evolution? Name any four vestigial
organs in human being.
4. Briefly explain the idea of natural selection taking industrial melanism or antibiotic resistance in
bacteria as example.
Ans. Prior to industrialization, number and frequency of white peppered moth far exceeded that of dark
coloured peppered moth in Liverpool , England . Since the white moth got selective advantage over
dark variety to avoid predation by concealing in the lichen infested grey tree trunk. However, after
industrialization, due to disappearance of lichen in a polluted ambience the dark peppered moth got
selective advantage over white moth to avoid predation in the black tree trunk and hence got
reproductive success due to directional selection. A reduction in air pollution due to clean air legislation
again lead to reproductive success of the white variety.
( industrial melanism)
5. What is geological time scale? How do you infer the evidence of evolution from it ?
6. Discuss the evidences from morphology and comparative anatomy in support of organic evolution.
7. Comparative embryology gives no less a significant evidence in support of evolution than any other
branch of biology. Substantiate.
8. Fossils are the documentary evidences in support of evolution. Discuss.
Ans Fossil record provides clear evidence for the evolution of species over time. It also documents the
evolution of major new groups of organisms from previously existing organisms. Fossil records allow
the biologist to reconstruct the history of life on earth.
9. Justify the statement" Galapagos islands are the living laboratories of Evolution".
Ans The Galapagos island are home to 13 species of finches which evolved on the Galapagos island in
isolation from other finches. New species of finches evolved from the single species that originally
colonized the island provide unique example of adaptive radiationthus , supporting evolution.
10. What is Hardy-Weinberg equilibrium? Write the Hardy-Weinberg equation.
11. What is genetic drift?
Ans :Genetic drift is the effect of chance.
Genetic drift causes random changes in allele frequencies over time. Genetic drift can cause small
populations to lose genetic variation. It can cause the fixation of harmful, neutral or beneficial alleles.
12. Define founder effect.
Ans Founder effect is a genetic bottle neck that results when a small group of individuals from a larger
source population establish a new population far from the original population.
13. What is gene flow?
Ans. Gene flow is nothing but exchanging alleles between populations.
Individuals within the populations differ in morphological, behavioral and biochemical traits, many of
which are under genetic control. Genetic variation provides the raw material on which evolution can
work.
Evolution can be summarized as a three step process• Mutations and genetic rearrangements caused by recombination occur at random.
• These random events then generate inherited differences in the characteristics of individuals in
populations.
• Finally, mutation, gene flow, genetic drift and natural selection can cause allele frequencies to
change over time.
• Of the four mechanisms of evolutionary change, mutation, gene flow and genetic drift are
influenced by chance events, while, natural selection is a random process.
16. Write short notes on Darwin’s finches.
Ans:
•
A divergent evolution has occurred in the ground
finches of Galapagos islands situated on the
equator, some 900 km west of equator.
•
Good example of adaptive radiation illustrated
by Charles Darwin. He differentiated thirteen
species of finches and grouped them into six
main types.
•
Finches in general possess stout, conical beaks
adapted for crushing seeds. But they have undergone great diversification in their feeding
habits. Accordingly shape and size of their beak has changed, ancestral finches on reaching
different islands occupied all empty ecological niches in absence of competition and evolved
into different species.
17. What are living fossils? Give examples.
Ans: Living fossil is an informal term for any living species (or clade) of organism which appears to be
the same as a species otherwise only known from fossils and which has no close living relatives. These
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HUMAN HEALTH AND DISEASE CHAPTER 8 74 COMMON INFECTIOUS DISEASES Refer to fig. 8.1 stages in lifecycle of plasmodium 75 STRUCTURE OF ANTIBODY MOLECULE
76 LIFECYCLE OF PLASMIDIUM 77 Lymphoid Organs
Primary Lymphoid
Organ
1. Bone Marrow
2.Thymus
Function:
Provide
microenvironment
For the development and
Maturation of lymphocyte
Secondary Lymphoid Organ
1. Spleen
2. Lymph Nodes
3. Peyer’s Patch
4. Tonsils
5. Mucosal associated lymphoid
tissue (MALT)
Function:
1. Spleen: Filter the microbes from blood
2. Lymph Nodes: Trap the microorganisms
3. Peyer’s Patch: Present in small intestine
and help In the formation of effector celles
4. Tonsils: Trap microbes entering through
Mouth
5. MALT: Traps Microbes
78 TYPES OF ACQUIRED IMMUNITY
ACTIVE IMMUNITY
- Antibody produced within own body
- it is long lasting
- Does not Cause allergy
- Takes time to activate
PASSIVE IMMUNITY
- Antibodies transferred from
another individual.
- Not long lasting.
- Sometimes cause allergy
-Provides immediate relief.
Types of Immune Response: 79 Types of Immune Response
Primary Response
- Exposure of body to pathogen for first
time
- Of Low Intensity
Secondary Response
- Subsequent exposure to same
pathogen
- Response of body is hieghtened
Vaccination and Immunization Vaccination refers to the administration of any vaccine. Immunization is the process by which the body produces antibodies in response to the vaccine to fight infections. Vaccine is a preparation of antigenic proteins of pathogens or inactivated/weakened pathogen. It is introduced into the body to generate antibodies which can neutralize the pathogens during actual infection. Vaccines also generate memory B & T cells that recognize the pathogens quickly. Vaccines that contain performed antibodies produce quick immune response and provide Passive Immunity e.g. vaccines against tetanus & snakebite. Other vaccines provide Active Immunity e.g. oral polio vaccine, BCG, cholera vaccine. Allergies The exaggerated response/hypersensitiveness of the immune system of a person to certain antigens coming in contact with or entering into the body is called allergy. Auto‐immunity It is a condition when structural & functional damage is caused due to the attack of the self cells of the body by its own immune cells .Examples : Rheumatoid arthritis, Insulin‐ dependent diabetes. 80 Refer Fig 8.6 replication of retrovirus page 155 NCERT
81 82 LIFE CYCLE OF PLASMODIUM Sprozoites are injected into the body by female anopheles mosquito Sporozoite reach theliver through blood Parasite reproduces asexually in the liver and comes out in the blood by bursting theliver cells They enter the RBC PARASITE REPRODUCE ASEXUALLY IN RBC and by bursting them releases haemozoin which causes cycles of fever Released parasite enter new RBC and infect them Parasite starts the sexual stage and forms gametocytes in RBC Female aanopheles mosquito takes up gametocytes Fertilization of gametes and development takes place in the mosquitoes intestine Mature infective sporozoite escape from the intestine and migrate to the salivary glands of mosquito Mosquito bites again and injects the sprozoites into human body 83 84 Chapter 8 human health and disease
IMPORTANT QUESTION
1) Why do children of metro cities of India suffer from allergies and asthma?
Ans (Hint.-Pollution )
2) A patient has lost his immunity. 1.How does saliva and tear help to prevent
bacterial infection?
Ans: -saliva and tear contain lysozymes.
-Lysozymes enzymes which digest the cell wall of bacteria
-By lysing the cell wall, they kill bacteria and prevent their infection.
2. What is vaccination ?How does it help to produce immunity?
Ans:- Vaccination process of introducing a preparation of antigenic protein of the
pathogens or weakened or killed pathogen in to the body.
-The vaccines include quick multiplication of B and T-lymphocytes; some of them are
stored as memory cells
-The B-lymphocytes quickly produce antibodies, which neutralize the antigen during
infection.
3.Write the full form of ELISA. Give an example of the clinical application of ELISA?
Ans:--Enzyme Linked Immune Sorbent Assay.
-ELISA test is used in the diagnosis of AIDS, hepatitis-Band other STD’s
4 .What are the advantages of people being healthy?
Ans-When people are healthy,
A)They are efficient at work which consequently increases productivity and brings
economic prosperity
B)Health increases longevity.
C)It reduces infant and maternal mortality
5 .A) Name the respective forms in which the malarial parasite gains entry into
I) Human body and
Ii) Body of female Anopheles
B) Name the hosts where the sexual and the asexual reproduction of malarial
parasite occur respectively
C) Name the toxin responsible for the appearance of symptoms of malaria in
humans. Why do these symptoms occur periodically ?
Ans-(A) (i)-Sporozoite
Define innate immunity. Name and explain the category of barrier which involves
macrophages.
Ans. Innate immunity refers to all those defence elements with which a person is born and
are always available to protect the body. -Macrophages form part of the cellular barrier. -The
cellular barrier includes the following specialized cells; (i) Polymorphonuclear leucocytes.
(ii) Monocytes. (iii) Natural killer lymphocytes and (iv) Macrophages. - these cells
phagocytose and destroy the invading microbes.
7. What is meant by writing H2L2 for an antibody? Name any four types of antibodies
produced in our/human body?
Ans. - Each antibody molecule has four peptide chains. - Of them, two are small and called
light chains (L) and two of them are longer and called heavy chains (H); hence written as
H2L2. The four types of antibodies are iga, ige, igg and igm.
8.How do normal cells get transformed into cancerous neoplastic cells?
Mention the differences between viral oncogenes and cellular oncogenes.
Ans.The transformation of normal cells into cancerous neoplastic cells is induced by
physical, chemical and biological agents collectively called carcinogens; they lose
the property of contact inhibition.
Difference: Viral Oncogenes
Cellular Oncogenes
- These are the genes present in the
oncogenic viruses, which effect
oncogenic transformation
of the cells they infect.
- These are the genes present in normal cells and
code for growth factors; when activated under certain
conditions, can cause oncogenic transformation of the
cell.
9(i) Explain metastasis. Why is it fatal?
Ans. (i) Metastasis is the property of tumor cells, which get separated from a tumor, spread to different
sites in the body through body fluids and produce secondary tumors wherever they are lodged. Since
secondary tumors are formed at several parts of the body, it is difficult to be diagnosed and treated;
hence it is fatal.
10 (1 ) Lymphocytes are of two types why are they called so?
A person was injured in a road accident and required an urgent immune response. What should be
done?
(ii) The lymphocytes are of two types B and T-cells. Why are they called so?
(iii) A person has injured on a road accident and required an urgent immune
response.
Ans: (i) Those lymphocytes which undergo maturation in the bone marrow are called
B-cells while those which undergo maturation in the thymus are called T-cells.
(ii) Those lymphocytes which undergo maturation in the bone marrow are called B-cells while those
which undergo maturation in the thymus are called T-cells.
Iii) Mention any one source for these chemicals.
Ans (Hint:- Drug Abuse)
Chapter-9 strategies for enhancement in food production
2.) Crossbreeding- superior males of one breed are mated with superior females of another
breed to get better progency.e.g.- cows of inferior breed with superior bull. Hisardale- is a new breed of
sheep developed in Punjab by crossing Bikaneri Eves and Marano Rams.
3) Interspecific hybridization- male and female animals of two different species are mated.
E.g.- mule is crossbreed of male donkey and female horse.
4) Control breeding- it is done by artificial insemination and multiple ovulation embryo transfer
technology (MOET)
(a)Artificial insemination- semen of superior male is collected and injected unto the reproductive tract
of selected female. The spread of certain diseases can be controlled by this method.
(b) MOET- Technique for herd improvement by successful production of hybrids.
i) Hormone(FSH) are administered to the cow for inducing follicular maturation and super ovulation. ii)
Cow produces 6-8 eggs instead of one egg & is either mated with elite bull or artificially inseminated. iii)
Fertilised egg at 8-32 cell stage are recovered non-surgically & transferred to surrogate mother. iv)
IDone in cattle, sheep, rabbits etc.
Steps in Plant breeding:1 Collection of variability-Collection and preservation of all different wild varieties, species, relatives
of cultivated species etc. are also called germplasm collection.
2.Evaluation and selection of parents-Germplasm is evaluated to identify plants with desirable traits.
3.Cross hybridization among the selected parents-Two plants having two desired characters are
hybridized to get new hybrid having two desired characters.
4.Selection and testing of superior recombinants-Selection of the plants having desired character
combinations.
5.Testing, release and commercialization of new cultivars-Newly selected lines are evaluated for
their yield, agronomic traits, disease resistance etc. and released into the market.
Green revolution - Crop production.
White revolution - Milk production
Blue revolution - Fish production
Biofortification-Breeding crops with higher levels of proteins, vitamins and minerals eg. Vit C rich bitter
gourd, mustard, tomato; protein rich beans lablab etc.
SCP (Single cell protein )Protein rich cell biomass from microbes such as bacteria, yeast, algae are used as alternative food.
Eg-Spirulina can be grown in waste water (from potato processing plant) to produce protein rich
biomass treated as food.
Advantages : i) Provides protein rich food supplement in human diet ii) Reduces pressure of
conventional agricultural production iii)Use of Waste water reduces pollution leveliv) High rate of
biomass production in large amount in short period.
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7.MicropropagationTissue culture technique used for rapid vegetative multilication of ornamental plants and fruit trees by
using small explants. Micropopagation is done by shoot meristem culture & somatic embryogeny. It
results in genetically identical plants & used widely in forestry & floriculture.
8.Somaclonal variation-Genetic variation in plants regenerated from a single culture is used to
develop several useful varieties eg., Short duration sugarcane, Rust resistant wheat.
Uses: a)Rapid clonal multiplication
b)Production of virus free plants
c)Production of transgenic plants
d)Germplasm collection
Questions
I MARK
Q1.Name two techniques involved in controlled breeding experiments.
Q2.What is blue and green revolution?
Q3. What is inbreeding depression?
Q4. What is ‘Heterosis’ or hybrid vigour?
Q5.Name the Indian variety of rice patented by an American company.
Q6.What is Pomato?
Q7 .Name the algae used as protein rich food.
Q8.Expand- MOET and SCP.
Q9.What is quarantine?
Q10.What is cultivar?
2 MARKS
Q1. What is Biofortification?
Q2.Which part of the plant is best suited for making virus free plants?
Q3.What is breed? What are the objectives of animal breeding?
Q4.Define out-crossing? Suggest an advantage.
Q5.What is artificial insemination? What is its importance?
Q6. What are the differences between aqua and pisciculture?
Q7. What is animal husbandry?
Q8. What is bird flu?
Q4. What is interspecific hybridization ? Give one example of crop in which it is practiced and mention
one advantage.
Q5. What is cross-breeding ? What advantages does it have? Give an example
5 MARKS QUESTIONS
Q1. Explain the points that have to be considered for successful bee- keeping?
Q2. Write the scientific name of sugarcane grown in north and south India respectively. Mention their
characteristic features. Mention the characteristic of the hybrid produced by crossing these two varieties
.
Hint :North – Saccharumbarberi. South – Saccharumofficinarum . High yield ,thick stems , higher sugar
content , ability to grow in both North and South India
Q 3. Describe various steps involved in plant breeding.
Hint: Collection of variability, Evaluation and selection of parents, Cross hybridisation among the
selected parents, Selection of testing of superior Recombinants, Testing , release and comercialisation
of new cultivars
LIST OF HIGH YIELD VARIETIES OF ANIMALS OF IMPORTANCE
Sl.
No.
01.
Animal
Name of breed
Distribution
Cattle
02.
Buffaloes
03.
Sheep
Gir
Malvi
Tharparkar
Murrah
Bhadawari
Nali
Shahabadi
Aseel
Gujrat
Rajasthan
Andhra Pradesh
Punjab
Uttar Pradesh
Jammu & Kashmin
Bihar
India
Chicken
02.
Wheat
Jaya
Ratna
Sonalika
Kalyan sona
India
India
India
India
Semi-dwarf
Semi-dwarf
High yield
Disease resistant
Chapter – 10: Microbes in Human Welfare
Microbes are present everywhere.
E.g. Thermal vents of geyser (Temp. above 1000c)
 Deep in soil.
 Under snow.
Diverse. Protozoa, Bacteria, Fungi, Virus, Viroids, Prions (Proteinaceous infectious agents)
Useful : Antibiotics.
Harmful: cause diseases.
In Household Products:
Everyday : Lactobacillus (LAB) Lactic acid Bacteria – form curd from milk.
 Increase Vit . B12
 Check disease causing microbes in our stomach.
Fermentation of dough for dosa, idli (CO2 produced)
Making bread –Baker’s yeast.Saccharomyces cerevisiae.
Antibiotics : (Against life)
Penicillin produced by Alexander Fleming from Penicillium notatum while working with Staphylococci
Earnest Chain and Howard Plorey awarded Nobel Prize in 1945 for establishing Penicillin as an
effective antibiotic.
Uses : Treat diseases like plague, whooping cough, diphtheria, leprosy.
Chemicals: Enymes and other Bioactivities Molecules:
Uses:
Aspergillus nigerfor production of Citric Acid.
Acetobacter aceti for production of Acetic Acid.
Clostridium butylicum for production of Butynic Acid.
Lactobacillus for production of Lactic acid.
Lipases used in detergents to remove oil strains from Laundry.
Pectinases and Proteases to clarify bottled jucies.
Streptokinase (from Streptococcus) as clot buster in patients with myocardial infraction (heart
attack).
Cyclosporin A– an immunosuppresant used in organ transplant patients (produced by Trichoderma
polysporum)
Statins produced by yeast Monascu spurpureus used as blood, cholesterol lowering agent.
Microbes in sewage Treatment:
Why treatment necessary?
Major component of waste water, human excreta.
Waste water sewage.
Cannot be disposed directly into rivers and streams.
Where & how?
Before disposal sewage treated in sewage treatment plants (STPs)
Treatment done in two stages.
 Primary : Physical removal of particles large and small by filtration and sedimentation.
Solids – primary sludge.
S
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ffl
t
Major part pumped into large anaerobic sludge digesters.
Anaerobic bacteria digest bacteria and fungi.
Bacteria produce gases such as menthane, hydrogen sulphide and CO2 – Biogas.
Secondary effluent released into rivers and streams.
No man made technology available till date.
Untreated sewage if released into rivers causes pollution.
Ministry of environment and Forests iniatiated, Ganga Action Plan and Yamuna Action Plan.
Biogas plant:
Concrete tank 10- 15 mts deep, slurry or dung fed.
Floating cover placed above rises as biogas content rises.
Connecting pipe for supply of biogas
Mode of spores operation.
oAvailable is sachets, mixed with water and sprayed on plants.
oEaten by insect larva
oToxin released in gut kills larvae.
Now Bt toxin genes introduced into plants – resistant to insect pests.
e.g. Bt cotton.
Tungus trichoderma now being developed.
Nucleo polyhedrovirus– good for narrow spectrum insecticide applications.
Advantages :No negative impacts on plants, mammals, birds, fish or target insects.
For overall IMP (Intergrated pest Management) programme.
For ecologically sensitive areas.
As Biofertilizers:
Chemical fertilizers major pollutant.
Switch to organic farming and use of biofertilizers need of the time.
Main sources of biofertilizers. Bacteria, Fungi & Cyanobacteria.
Eg Rhizobium present in roots of leguminious plants fix atmospheric nitrogen into usable organic form.
Azospirillium and Azotobacter – free living bacteria – fix atmospheric Nitrogen.
Symbiotic Associations
Eg.Genus Glomus sp. form mycorrhiza
Fungal symbiont absorbs phosphorus from soil and passes it to plant.
Plants show
• resistance to root – borne pathogens.
• Tolerance to salinity and drought
• Increase in growth and development.
Cynobacteria– autotrophic – fix atmospheric nitrogen
Imp.biofertilizer.
e.g. Anabaena, Nostoc, Oscillatoria.
Blue green algae – increase fertility by adding organic matter.
No. of biofertilizers are commercially available.
For production of biodegradable plastics:
biodegradable plastic, e.g. polyhydroxybutyrate (PHB) is being produced commercially by fermentation
with the bacterium Alcaligenes eutrophus.
Production of PHB may be easily achieved in tree plants like populous, where PHB can be extracted
Process of sewage treatment in STP
a)Primary treatment(physical )
b)Secondary treatment(biological)
Effluent loaded in large aeration tank, Agitation & rapid growth of aerobic microbes (flocs) ,Consumes
organic matter ,reduces BOD, Effluent passed to settling tank, Flocs sediments form – activated
sludge(A.S.),Poured into sludge digester(small amount of A.S. used as inoculum) Filtration &
sedimentation.
Process of sewage treatment in STP
Primary treatment (physical)
Filtration & sedimentation
Secondary treatment (biological)
Filtration &sedimentation
Agitation & rapid growth of aerobic microbes (flocs)
Consumes organic matter, reduces BOD
Effluent passed to settling tank
Flocs sediments form – activated sludge
Anaerobic Sludge Digester
Form Biogas
Water released into rivers and
streams
Questions
(1 mark)
1. Name two vitamins produced by microbial fermentation.
2. What is the botanical name of baker‘s yeast?
3. Milk starts to coagulate when lactic acid bacteria is added to warm milk as a starter. Mention two
benefits LAB provides.
4. Name any two antibiotics produced from microbial action.
Ans: Penicillin – Penicillium notatum
Streptomycin- Streptomyces griseus
5. Name any two human therapeutic proteins produced in bacteria.
Ans: human insulin hepatitis B surface antigen human growth hormone interferons etc
6. What is micorrhiza? How does it help as biofertilizers?
7. What is BOD? What does it mean if a water sample has more BOD?
8. Name any two Cyanobacteria. How do they serve as main source of biofertilizer ?
9. What is the difference between Bt and Bt cotton? Explain the use of Bt as a biological control.
10. Give reasona) Bottled fruit juices brought from market are clearer as compared to those made at home,
b) Large holes are found in swiss-cheese,
c) The insect which are so called pest are not eradicated in organic fumes.
11. Name the gobar gas liberated from biogas plant. Which type of bacteria are responsible for its
production? Give advantage.
12. What do you mean by GRAS?
Ans: GRAS means ‘generally regarded as safe category’ which includes microbes which are nonpathogenic, non-toxic, non-antibiotic producing etc. These are generally used as hosts for production of
recombinant molecules.
14. What is ‘Golden Rice’? In what why is it different from normal rice?
Ans: The staple food rice is extremely low in vitamin A and therefore the improvement of vitamin A
required. Prof. Ingo Potrykus and Dr. Peter Beyer developed genetically engineered rice which is
enriched in pro-vitamin A (beta-carotenoid) by introducing three genes involved in the biosynthetic
pathway for carotenoid. It is called ‘golden rice’, the seeds are yellow in colour because of pro-vitamin A
is produced in the entire grain.
15. What do you mean by ‘flavr savr’ tomato’?
Ans: These are transgenic tomatoes commercialized in U.S with longer shelf life due to slow ripening.
Gas hormone, ethylene is involved in the regulation of fruit ripening. Therefore, ripening can be slowed
down by blocking or reducing ethylene production.
(3 marks)
1. Differentiate between
a) Primary sludge and activated sludge,
b) Biofertilizer and chemical fertilizer,
c) Primary sewage treatment and secondary sewage treatment.
(5 marks)
1.Answer briefly:
1) How is sewage harmful to man?
2) What is organic farming?
3) Which group of organisms attack insect and arthropod? How are they best biocontrol biological
t
•
•
from organisms in the system and inserting it into a model organism. The model organism then
expresses this DNA where it can be studied using standard laboratory techniques.
Employed as a means of systematically investigating, classifying, and manipulating the entire
genetic material isolated from environmental samples.
A multi-step process that relies on the efficiency of four main steps (see Figure) which are (i)
the isolation of genetic material, (ii) manipulation of the genetic material, (iii) library
construction, and the (iv) the analysis of genetic material in the metagenomic library.
Applications of Metagenomics
•
Many microorganisms have the ability to degrade waste products, make new drugs for medicine,
make environmentally friendly plastics, or even make some of the ingredients of food we eat. By
isolating the DNA from these organisms, it provides us with the opportunity to optimize these
processes and adapt them for use in our society.
•
Information from metagenomic libraries has the ability to enrich the knowledge and applications of
many aspects of industry, therapeutics, and environmental sustainability. This information can then
be applied to society in an effort to create a healthy human population that lives in balance with the
Chapter-11: BIOTECHNOLOGY: PRINCIPLES AND PROCESSES
CONCEPT MAP :-
Biotechnology is a broad area of science involving multiple disciplines designed to use living
4. The resulting recombinant plasmid is returned to the bacterial cell.
5. The bacteria reproduce and the required gene is cloned.
How do we obtain DNA and how do we manipulate DNA?
Quite straightforward to isolate DNA
For instance, to isolate genomic DNA
1.
2.
3.
4.
5
Remove tissue from organism
Homogenise in lysis buffer containing guanidine thiocyanate (denatures proteins)
Mix with phenol/chloroform - removes proteins
Keep aqueous phase (contains DNA)
Add alcohol (ethanol or isopropanol) to precipitate DNA from solution
- Digestion
- Fractionation
- Purification of the TARGET fragment
- Cloning into vectors
- Transformation of host cell and selection
- Replication
- Analysis
Introduction of recombinant DNA into host cells:
Some commonly used procedures:
1. Transformation
2. Transfection
3. Electroporation
4. Biolistics
5. Agrobacterium mediated gene transfer
DNA is manipulated using various enzymes that modify and/or synthesise it
Until 1970 there were no convenient methods available for cutting DNA into discrete, manageable
fragments.
1970 - The Beginning of the Revolution
Discovery of a restriction enzyme in the bacterium Haemophilus influenzae
Restriction enzymes
. Restriction enzymes are endonucleases
•
•
•
•
•
Bacterial enzymes .
Different bacterial strains express different restriction enzymes.
The names of restriction enzymes are derived from the name of the bacterial strain
they are isolated from.
Cut (hydrolyse) DNA into defined and REPRODUCIBLE fragments.
Basic tools of gene cloning .
Names of restriction endonucleases
Titles of restriction enzymes are derived from the first letter of the genus +
the first two letters of the species of organism from which they were isolated.
Source microorganism
Enzyme
Recognition Site
AG CT
Ends produced
Arthrobacter luteus
Alu I
Bacillus amyloiquefaciens H
Bam HI
G GATCC
Blunt
Sticky
Escherichia coli
Eco RI
G AATTC
Sticky
Haemophilus gallinarum
Hga I
GACGC(N)5
Sticky
Haemophilus infulenzae
Hind III
A AGCTT
Sticky
Providencia stuartii 164
Pst I
CTGCA G
Sticky
Deleted:
This is known as a Restriction Site
The phosphodiester bond is cleaved between specific bases, one on each DNA strand
The product of each reaction is two double stranded DNA fragments
Restriction enzymes do not discriminate between DNA from different organisms
Restriction endonucleases are a natural part of the bacterial defence system
• Part of the restriction/modification system found in many bacteria
• These enzymes RESTRICT the ability of foreign DNA (such as bacteriophage DNA) to
infect/invade the host bacterial cell by cutting it up (degrading it)
• The host DNA is MODIFIED by METHYLATION of the sequences these enzymes
recognise
o Methyl groups are added to C or A nucleotides in order to protect the bacterial
host DNA from degradation by its own enzymes
Type II Recognise a specific target sequence in DNA, and then break the DNA (both strands), within or
close to, the recognition site.Only they are used in rDNA technology as they recognize and cut DNA
within a specific sequence typically consisting of 4-8 bp.
e.g. EcoRI
Usually require Mg2+
• Type III Intermediate properties between type I and type II. Break both DNA strands at
a defined distance from a recognition site
o e.g. HgaI
o Require Mg2+ and ATP
Hundreds of restriction enzymes have been isolated and characterised
• Enables DNA to be cut into discrete, manageable fragments
• Type II enzymes are those used in the vast majority of molecular biology techniques
• Many are now commercially available
Many Type II restriction endonucleases recognise PALINDROMIC sequences (From Greek
palindromos, running back again, recurring :palin, again)
A segment of double-stranded DNA in which the nucleotide sequence of one strand reads in reverse
order to that of the complementary strand. (always read from the same direction)
For example, EcoRI recognises the sequence
5'-G A A T T C-3'
o
o
3'-C T T A A G-5'
Different enzymes cut at different positions and can create single stranded ends ('sticky ends')
•
Some generate 5' overhangs - eg: EcoRI
•
Some generate 3' overhangs - eg: PstI
Some generate blunt ends- eg: SmaI
•
Inserting foreign DNA into a cloning vector
Restriction enzymes are a useful tool for analysing Recombinant DNA
After ligating a particular DNA sequence into a cloning vector, it is necessary to check that the correct
fragment has been taken up. Sometimes it is also necessary to ensure that the foreign DNA sequence
is in a certain orientation relative to sequences present in the cloning vector.
•
•
•
Checking the size of the insert
Checking the orientation of the insert
Determining pattern of restriction sites within insert DNA
DNA fractionation
Separation of DNA fragments in order to isolate and analyse DNA cut by restriction enzymes
Electrophoresis
Electrophoresis is a technique used to separate and sometimes purify macromolecules - especially
proteins and nucleic acids - that differ in size, charge or conformation. When charged molecules are
placed in an electric field, they migrate toward either the positive or negative pole according to their
charge.
DNA is electrophoresed through the agarose gel from the cathode (negative) to the anode(positive)
when a voltage is applied, due to the net negative charge carried on DNA.
When the DNA has been electrophoresed, the gel is stained in a solution containing the chemical
ethidium bromide. This compound binds tightly to DNA and fluoresces strongly under UV light allowing the visualisation and detection of the DNA.
Recombinant DNA technology:
Isolated DNA is cloned into VECTORS for long term storage, propagation of the DNA and for
production of protein from gene(s) encoded in the DNA
What are cloning vectors?
Cloning vectors are extra-chromosomal 'replicons' of DNA which can be isolated and can replicate
independently of the chromosome. Vectors usually contain a selectable marker - a gene that allows
selection of cells carrying the vector e.g. by conferring resistance to a toxin. DNA of interest can be
cloned into the vector and replicated in host cells, usually one which has been well characterised.
Commonly used vector systems
• Bacterial plasmids
• Bacteriophages
• Cosmids
• Yeast artificial chromosomes (YACs)
• Ti plasmid (plants)
• Eukaryotic viruses such as baculovirus (insect cells), SV40 virus and retroviruses.
Characteristics of a Cloning Vector
™ Origin of replication (ORI)
This process marks autonomous replication in vector. ORI is a specific sequence of nucleotide in DNA
from where replication starts. When foreign DNA is linked to this sequence then along with vector
replication, foreign (desirable) DNA also starts replicating within host cell.
™ Selectable Marker
Charecteristics of Selectable marker:
A gene whose expression allows one to identify cells that have been transforrned or transfected
with a vector containing the marker gene.
A marker gene is used to determine if a piece of DNA has been successfully inserted into the host
organism. Gene usually encoding resistance to an antibiotic. A selectable marker will protect the
organism from a selective agent that would normally kill it or prevent its growth.
™ Restriction sites
Allow cleavage of specific sequence by specific Restriction Endonuclease. Restriction sites in
E.coli cloning vector pBR322 include HindIII , EcoRI , BamHI , SalI, PvuI, PstI, ClaI etc.
Refer NCERT text book diagram of pBR322
A Cloning Vector that Works with Plant Cells
Most commonly used plant cloning vector "Ti" plasmid, or tumor-inducing plasmid. Found in cells of
the bacterium known as Agrobacterium tumefaciens, normally lives in soil. Bacterium has ability to
infect plants and cause a crown gall, or tumorous lump, to form at the site of infection.
Ti plasmid - called T DNA - separates from the plasmid and incorporates into the host cell genome. This
aspect of Ti plasmid function has made it useful as a plant cloning vector (natural genetic engineer).
Plasmids are the most commonly used vector system. Several types available for cloning of foreign
DNA in the host organism Escherichia coli. Many E. coli plasmids allow the expression of proteins
encoded by the cloned DNA
Bacteriophage another common vector system used for cloning DNA. These are viruses which 'infect'
E. coli. The M13 bacteriophage is a single-stranded DNA virus which replicates in E. coli in a double-
Insertional inactivation Subcloning a DNA fragment into an active gene (usually a marker gene whose function can be easily
detected) will disrupt the function of that gene. This can be detected by looking for colonies that no
longer display that phenotype.
Colour selection
A more common method to determine which transformants contain plasmids with inserts is to use
colour selection. For E. coli, this involves the lac complex and blue/white screening.
Colonies carrying plasmid with no insert will be coloured blue whereas colonies carrying recombinant
plasmid will be white.
For plasmids such as pBR322, which contains two antibiotic resistance genes, cloning an insert into
one of these will disrupt that gene and inactivate the resistance to that antibiotic.
Southern/Northern Blotting Analysis
Analysing complex nucleic acid mixtures (DNA or RNA)
The total cellular DNA of an organism (genome) or the cellular content of RNA are complex mixtures of
different nucleic acid sequences. Restriction digest of a complex genome can generate millions of
specific restriction fragments and there can be several fragments of exactly the same size which will not
be separated from each other by electrophoresis.
Techniques have been devised to identify specific nucleic acids in these complex mixtures
• Southern blotting - DNA
• Northern blotting - RNA
Southern blotting
Technique devised by Ed Southern in 1975, is a commonly used method for the identification of DNA
fragments that are complementary to a know DNA sequence. Allows a comparison between the
genome of a particular organism and that of an available gene or gene fragment ( probe). It can tell us
whether an organism contains a particular gene (DNA fragment) or not
In Southern blotting,
1. Chromosomal DNA is isolated from the organism of interest, and digested to completion with a
restriction endonuclease enzyme.
Fig 7-32, Lodish et al (4th ed.)
DNA is bound irreversibly to the filter/membrane by baking at high temperature (nitrocellulose) or crosslinking through exposure to UV light (nylon).
Final step is to immerse the membrane in a solution containing the probe - either a DNA (cDNA clone,
genomic fragment, oligonucleotide or RNA ) can be used. This is DNA hybridisation
The membrane is washed to remove non-specifically bound probe, and is then exposed to X-ray film - a
process called autoradiography. The principle of Southern blotting
been shown that PCR can be used to generate a detectable quantity of DNA from only one starting
target (or template) molecule.
PCR developed in the mid-1980's, has found multiple applications, such as:
1. Rapid amplification of intact genes or gene fragments
2. Generation of large amounts of DNA for sequencing
3. Generation of probes specific for uncloned genes by selective amplification of a
specific segment of cDNA
4. Analysis of mutations for medical applications
5. Detection of minute amounts of DNA for forensic purposes
6. Amplification of chromosomal regions adjacent to genes of known sequence and many
more·
Development of PCR won the Nobel prize for Kary Mullis and co-workers.
PCR principle
PCR reaction is a DNA synthesis reaction that depends on the extension of primers annealed to
opposite strands of a dsDNA template that has been denatured (melted apart) at temperatures near
boiling. By repeating the melting, annealing and extension steps, several copies of the original
template DNA can be generated.
The amount of starting material (target) needed is very small
Not necessary to isolate the desired sequence, because it will be defined by the primers that are used
in the reaction. The primers are oligonucleotides complementary to different regions on the 2 strands
of DNA template (flanking the region to be amplified).
The primer acts as a starting point for DNA synthesis. The oligo is extended from its 3' end by DNA
polymerase.
Primer design
PCR is a cycle of three steps:
The stages of a PCR reaction
1. DENATURATION - the strands of the DNA are melted apart by heating to 95°C
2. ANNEALING - the temperature is reduced to ~ 55°C to allow the primers to anneal to
the target DNA
3. POLYMERISATION / EXTENSION - the temperature is changed to the optimum
temperature for the DNA polymerase to catalyse extension of the primers, i.e. to copy
the DNA between the primers.
The cycle is repeated over and over again - as many times as needed to produce a detectable amount
of product.
Discovery of a thermostable DNA polymerase
The breakthrough came with the discovery of the thermostable DNA polymerase Taq
polymerase, from the thermophilic bacterium, Thermus aquaticus, which lives in hot springs.
Taq polymerase enzyme can resist high temperatures required to melt the template DNA apart
without denaturation (loss of activity) and works best at high temperatures (72°C). This led to
improved specificity & sensitivity. Annealing of primers to sites other than the target sequence is
significantly reduced at the higher temperatures used for Taq polymerase.
Applications of PCR
1) Cloning a gene encoding a known protein
2) Amplifying 'old DNA'
3) Amplifying cloned DNA from vectors
4) Creating mutations in cloned genes
5) Rapid amplification of cDNA ends - RACE
6) Detecting bacterial or viral infection
* AIDs infection
* Tuberculosis (Mycobacterium tuberculosis)
7) Cancer
Detecting mutations that occur in cancer and monitoring cancer therapy. Determining if a patient is free
of malignant cells
8) Genetic diagnosis
a. Diagnosing inherited disorders
Downstream processing
It refers to the recovery and purification of biosynthetic products, particularly pharmaceuticals, from
natural sources such as animal or plant tissue or fermentation broth
Stages in Downstream Processing
A widely recognized heuristic for categorizing downstream processing operations divides them into four
groups which are applied in order to bring a product from its natural state as a component of a tissue,
cell or fermentation broth through progressive improvements in purity and concentration.
Removal of insolublesProduct Isolation
Product Purification
Product Polishing
GLOSSARY:
Adult stem cells
The stem cells found in a developed organism and have the twin properties of self-renewal and
differentiation. These can be obtained from fetal cord blood and bone marrow. They are multipotent in
nature.
Amplification
An increase in the number of copies of a specific DNA fragment; can be in vivo or in vitro.
See also:cloning, polymerase chain reaction
Annotation
Adding pertinent information such as gene coded for, amino acid sequence, or other complementary to
the database entry of raw sequence of DNA bases.
Antisense
Nucleic acid that has a sequence exactly opposite to an mRNA molecule made by the body; binds to
the mRNA molecule to prevent a protein from being made.
Antisense RNA technology
An RNA molecule that is the reverse complement of a naturally occurring mRNA, and which can be
used to prevent translation of that mRNA in a transformed cell.
Autoradiography
A technique that uses X-ray film to visualize radioactively labeled molecules or fragments of molecules;
used in analyzing length and number of DNA fragments after they are separated by gel electrophoresis.
Remarkable method developed to introduce foreign DNA into mainly plant cells is by using a gene or
particle gun. Microscopic particles of gold or tungsten are coated with the DNA of interest and
bombarded onto cells with a device much like a particle gun. Hence the term biolistics is used.
Biotechnology
Set of biological techniques developed through basic research and now applied to research and
product development. In particular, biotechnology refers to the use by industry of recombinant DNA, cell
fusion, and new bioprocessing techniques.
Cancer
Diseases in which abnormal cells divide and grow unchecked. Cancer can spread from its original site
to other parts of the body and can be fatal.
See also:hereditary cancer, sporadic cancer
Carcinogen
Something which causes cancer to occur by causing changes in a cell's DNA.
See also:mutagen
Carrier
An individual who possesses an unexpressed, recessive trait.
cDNA library
A collection of DNA sequences that code for genes. The sequences are generated in the laboratory
from mRNA sequences.
See also:messenger RNA
Cell
The basic unit of any living organism that carries on the biochemical processes of life.
Chromosome
The self-replicating genetic structure of cells containing the cellular DNA that bears in its nucleotide
sequence the linear array of genes. In prokaryotes, chromosomal DNA is circular, and the entire
genome is carried on one chromosome. Eukaryotic genomes consist of a number of chromosomes
whose DNA is associated with different kinds of proteins.
Clone
An exact copy made of biological material such as a DNA segment (eg. a gene or other region), a
whole cell, or complete organism.
Cloning
Using specialized DNA technology to produce multiple, exact copies of a single gene or other segment
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Complementary DNA (cDNA)
DNA that is synthesized in the laboratory from a messenger RNA template.
Complementary sequence
Nucleic acid base sequence that can form a double-stranded structure with another DNA fragment by
following base-pairing rules (A pairs with T and C with G). The complementary sequence to GTAC for
example, is CATG.
Cosmid
Artificially constructed cloning vector containing the cos gene of phage lambda. Cosmids can be
packaged in lambda phage particles for infection into E. coli; Permits cloning of larger DNA fragments
(up to 45kb) than can be introduced into bacterial hosts in plasmid vectors.
Crossing over The breaking during meiosis of one maternal and one paternal chromosome, the
exchange of corresponding sections of DNA, and the rejoining of the chromosomes. This process can
result in an exchange of alleles between chromosomes.
See also:recombination
DNA (deoxyribonucleic acid)
The molecule that encodes genetic information. DNA is a double-stranded molecule held together by
weak bonds between base pairs of nucleotides. The four nucleotides in DNA contain the bases adenine
(A), guanine (G), cytosine (C), and thymine (T). In nature, base pairs form only between A and T and
between G and C; thus the base sequence of each single strand can be deduced from that of its
partner.
DNA bank
A service that stores DNA extracted from blood samples or other human tissue.
DNA profiling
A PCR technique that determines the alleles present at different STR (short tandem repeat) loci within a
genome in order to use DNA information to identify individuals.
DNA repair genes
Genes encoding proteins that correct errors in DNA sequencing.
DNA replication
The use of existing DNA as a template for the synthesis of new DNA strands. In humans and other
eukaryotes, replication occurs in the cell nucleus.
DNA sequence
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Electroporation
A process using high-voltage current to make cell membranes permeable to allow the introduction of
new DNA; commonly used in recombinant DNA technology.
See also:transfection
Embryonic stem (ES) cells
An embryonic cell having totipotency that can replicate indefinitely, transform into other types of cells,
and serve as a continuous source of new cells. These cells are derived from inner cell mass of the
blastocyst or the 4-8 cell stage of embryo.
Endonuclease
See:restriction enzyme
Escherichia coli
Common bacterium that has been studied intensively by geneticists because of its small genome size,
normal lack of pathogenicity, and ease of growth in the laboratory.
Eugenics
Study of improving a species by artificial selection; usually refers to the selective breeding of humans.
Exogenous DNA
DNA originating outside an organism that has been introduced into the organism.
Exon
The protein-coding DNA sequence of a gene.
See also:intron
Exonuclease
An enzyme that cleaves nucleotides sequentially from free ends of a linear nucleic acid substrate.
Expressed sequence tag (EST)
A short strand of DNA that is part of cDNA molecule and can act as identifier of a gene. Used in
locating and mapping genes.
See also:cDNA, sequence tagged site
Fingerprinting
In genetics, the identification of multiple specific alleles on a person's DNA to produce a unique
identifier for that person.
See also:forensics
Fluorescence in situ hybridization (FISH)
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Gene
The fundamental physical and functional unit of heredity. A gene is an ordered sequence of nucleotides
located in a particular position on a particular chromosome that encodes a specific functional product
(i.e., a protein or RNA molecule)
See also:gene expression
Gene expression
The process by which a gene's coded information is converted into the structures present and operating
in the cell. Expressed genes include those that are transcribed into mRNA and then translated into
protein and those that are transcribed into RNA but not translated into protein (eg. transfer and
ribosomal RNAs).
Gene gun or particle gun: a popular and widely used direct gene transfer method for delivering
foreign genes into virtually any tissues and cells or even intact seedlings.
• The foreign DNA is coated or precipitated onto the surface of minute gold or tungsten particles (1-3
µm).
• It is bombarded or shot onto the target tissue or cells using the gene gun or microprojectile gun or
shot gun.
• The bombarded cells or tissues are cultured on selection medium to regenerate plants from the
transformed cells.
Gene library
See:genomic library
Gene mapping
Determination of the relative positions of genes on a DNA molecule (chromosome or plasmid) and of
the distance, in linkage units or physical units, between them.
Gene pool
All the variations of genes in a species.
See also:allele, gene,polymorphism
Gene therapy
Experimental procedure aimed at replacing, manipulating, or supplementing nonfunctional or
misfunctioning genes with healthy genes.
See also:gene, inherit, somatic cell gene therapy, germ line gene therapy
Gene transfer
Incorporation of new DNA into an organism's cells, usually by a vector such as a modified virus. Used
in gene therapy.
See also:mutation, gene therapy,vector
See:genome
Genetic polymorphism
Difference in DNA sequence among individuals, groups, or populations (e.g., genes for blue eyes
versus brown eyes).
Genetic screening
Testing a group of people to identify individuals at high risk of having or passing on a specific genetic
disorder.
Genetic testing
Analyzing an individual's genetic material to determine predisposition to a particular health condition or
to confirm a diagnosis of genetic disease.
Genetics
The study of inheritance patterns of specific traits.
Genome
All the genetic material in the chromosomes of a particular organism; its size is generally given as its
total number of base pairs.
Genome project
Research and technology-development effort aimed at mapping and sequencing the genome of human
beings and certain model organisms.
See also:Human Genome Initiative
Genomic library
A collection of clones made from a set of randomly generated overlapping DNA fragments that
represent the entire genome of an organism.
Genotype
The genetic constitution of an organism, as distinguished from its physical appearance (its phenotype).
Human Genome Project (HGP)
Formerly titled Human Genome Initiative.
See also:Human Genome Initiative
In situ hybridization
Use of a DNA or RNA probe to detect the presence of the complementary DNA sequence in cloned
bacterial or cultured eukaryotic cells.
In vitro
Studies performed outside a living organism such as in a laboratory.
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Informatics
See:bioinformatics
Karyotype
Photomicrograph of an individual's chromosomes arranged in standard format showing the number,
size, and shape of each chromosome type; used in low-resolution physical mapping to correlate gross
chromosomal abnormalities with the characteristics of specific diseases.
Knockout
Deactivation of specific genes; used in laboratory organisms to study gene function.
See also:gene, locus, model organisms
Marker
See:genetic marker
Microinjection
A technique for introducing a solution of DNA into a cell using a fine microcapillary pipette or
microsyringe under a phase contrast microscope to aid vision.
Microsatellite DNA
Polymorphism comprising tandem copies of usually, two-, three-, four- or five-nucleotide repeat units,
also called a short tandem repeat (STR).
Mitochondrial DNA
The DNA located inmitochondria, Mitochondrial DNA can be regarded as the
smallest chromosome. Human mitochondrial DNA was the first significant part of the human
genome to be sequenced. In most species, including humans, mtDNA is inherited solely from the
mother.
Mutation
It is an alteration in any of the base of a DNA sequence sometime’s leading to a defective protein or
prematurely terminated non-functional protein. Mutations are spontaneous in nature although rare.
Example-Sickle cell haemoglobin has amino acid mutation of valine to glutamine in its beta chain.
Nitrogenous base
A nitrogen-containing molecule having the chemical properties of a base. DNA contains the nitrogenous
bases adenine (A), guanine (G), cytosine (C), and thymine (T).
See also:DNA
Northern blot
A gel-based laboratory procedure that locates mRNA sequences on a gel that are complementary to a
piece of DNA used as a probe.
Autonomously replicating extra-chromosomal circular DNA molecules, distinct from the normal bacterial
genome and nonessential for cell survival under nonselective conditions. Some plasmids are capable of
integrating into the host genome. Number of artificially constructed plasmids are used as cloning
vectors.
Plaque
A zone of clearing on a lawn of bacteria caused by lysis of the cells by infecting phage particles.
Pilot plant
The manufacturers try to validate laboratory process on an intermediate scale before attempting
commercial production. Step is carried out in a pilot plant, a mini version of the commercial plant.
Polymerase chain reaction (PCR)
A method for amplifying a DNA base sequence using heat-stable polymerase and two 20-base primers,
one complementary to the (+) strand at one end of the sequence to be amplified and one
complementary to the (-) strand at the other end. Because the newly synthesized DNA strands can
subsequently serve as additional templates for the same primer sequences, successive rounds of
primer annealing, strand elongation, and dissociation produce rapid and highly specific amplification of
the desired sequence. PCR also can be used to detect the existence of the defined sequence in a DNA
sample.
Polymerase, DNA or RNA
Enzyme that catalyzes the synthesis of nucleic acids on preexisting nucleic acid templates, assembling
RNA from ribonucleotides or DNA from deoxyribonucleotides.
Primer
Short preexisting polynucleotide chain(generally from 17-30 nucleotides in length) to which new
deoxyribonucleotides can be added by DNA polymerase.
Probe
Single-stranded DNA or RNA molecules of specific base sequence, labeled either radioactively or
immunologically. Used to detect the complementary base sequence by hybridization.
Promoter
The nucleotide sequence upstream of a gene that acts as a signal for RNA polymerase binding.
RACE (rapid amplification of cDNA ends)
A PCR-based technique for mapping the end of an RNA molecule.
Restriction enzyme, endonuclease
Protein that recognizes specific, short nucleotide sequences and cuts DNA at those sites. Bacteria
Specific nucleotide sequence of DNA at which a particular restriction enzyme cuts the DNA. Some sites
occur frequently in DNA (e.g., every several hundred base pairs); others much less frequently (rarecutter; e.g., every 10,000 base pairs).
Retroviral infection
Presence of retroviral vectors, such as some viruses, which use their recombinant DNA to insert their
genetic material into the chromosomes of the host's cells. The virus is then propogated by the host cell.
Reverse transcriptase
Enzyme used by retroviruses to form a complementary DNA sequence (cDNA) from their RNA. The
resulting DNA is then inserted into the chromosome of the host cell.
Reverse transcription-PCR (RT-PCR)
PCR technique in which the starting material is RNA. The first step in the procedure is conversion of the
RNA to cDNA with reverse transcriptase.
Ribonucleotide
See:nucleotide
Ribose
The five-carbon sugar that serves as a component of RNA.
See also:ribonucleic acid, deoxyribose
Ribosomal RNA (rRNA)
A class of RNA found in the ribosomes of cells.
RNA (Ribonucleic acid)
Chemical found in nucleus and cytoplasm of cells. Plays important role in protein synthesis and other
chemical activities of the cell.Structure of RNA similar to that of DNA. There are several classes of RNA
molecules, including messenger RNA, transfer RNA, ribosomal RNA, and other small RNAs, each
serving a different purpose.
Sanger sequencing
• A widely used method of determining the order of bases in DNA.
•
The classical chain-termination method requires a single-stranded DNA template, a DNA primer, a
DNA polymerase, normal deoxynucleotide triphosphates (dNTPs), and modified nucleotides
(dideoxy NTPs) that terminate DNA strand elongation.
Satellite
Chromosomal segment that branches off from the rest of the chromosome but is still connected by a
thin filament or stalk.
Scaffold
In genomic mapping, a series of contigs that are in the right order but not necessarily connected in one
continuous stretch of sequence.
Segregation
The normal biological process whereby the two pieces of a chromosome pair are separated during
meiosis and randomly distributed to the germ cells.
Sequencing
Determination of order of nucleotides (base sequences) in a DNA or RNA molecule or the order of
amino acids in a protein.
The X or Y chromosome in human beings that determines the sex of an individual. Females have two X
chromosomes in diploid cells; males have an X and a Y chromosome. The sex chromosomes comprise
the 23rd chromosome pair in a karyotype.
Shotgun method
Sequencing method that involves randomly sequenced cloned pieces of the genome, with no
foreknowledge of where the piece originally came from. This can be contrasted with "directed"
strategies, in which pieces of DNA from known chromosomal locations are sequenced. Because there
are advantages to both strategies, researchers use both random (or shotgun) and directed strategies in
combination to sequence the human genome.
Shuttle vector
A vector that can replicate in the cells of more than one organism (e.g. YAC vector in E.coli and in
yeast).
Single nucleotide polymorphism (SNP)
DNA sequence variations that occur when a single nucleotide (A, T, C, or G) in the genome sequence
is
altered.
Single-gene disorder
Hereditary disorder caused by a mutant allele of a single gene (e.g., Duchenne muscular dystrophy,
retinoblastoma, sickle cell disease).
See also:polygenic disorders
Site-directed mutagenesis
Technique Biotechnologist use to create mutation selectively, rather than that which occurs randomly in
nature Using this technique amino acids can be substituted in the expressed proteins making them
Transfer RNA (tRNA)
A class of RNA having structures with triplet nucleotide sequences that are complementary to the triplet
nucleotide coding sequences of mRNA. The role of tRNAs in protein synthesis is to bond with amino
acids and transfer them to the ribosomes, where proteins are assembled according to the genetic code
carried by mRNA.
Transgenic
An experimentally produced organism in which DNA has been artificially introduced and incorporated
into the organism's germ line.
See also:cell, DNA, gene, nucleus, germ line
Transposable element
A class of DNA sequences that can move from one chromosomal site to another.
Transformation
Most common method to introduce rDNA into living cells. In this procedure, bacterial cells take up DNA
from the surrounding environment. Many host cell organisms such as E.coli, yeast and mammalian
cells do not readily take up foreign DNA and have to be chemically treated to become competent to do
so. In 1970, Mandel and Higa found that E.coli cells become markedly competent to take up external
DNA when suspended briefly in cold calcium chloride solution.
CaCl2 known to increase the efficiency of DNA uptake to produce transformed bacterial cells. The
divalent Ca2+ ions supposedly create transient pores on the bacterial cell wall by which the entry of
foreign DNA is facilitated into the bacterial cells.
Transfection
Another method to transfer rDNA into host cells involves mixing the foreign DNA with charged
substances like calcium phosphate, cationic liposomes or DEAE dextran and overlaying on recipient
animal cells.
Trisomy
Possessing three copies of a particular chromosome instead of the normal two copies.
See also:cell, gene, gene expression, chromosome
Vector
DNA molecule, capable of replication in a host organism, into which a gene in inserted to construct a
recombinant DNA molecule.
Virus
Noncellular biological entity that can reproduce only within a host cell. Viruses consist of nucleic acid
covered by protein; some animal viruses are also surrounded by membrane. Inside the infected cell, the
virus uses the synthetic capability of the host to produce progeny virus
Outline of molecular biology
Questions
1 Mark Questions
12) Name the microorganism from which the thermostable DNA polymerase required for PCR is
obtained?
13) What is a bioreactor?
14) What are the two main processes involved in downstream processing?
15) Do eukaryotic cells have restriction endonucleases? Justify your answer.
HINTS:
1) Large scale production and marketing of products and processes using living organisms, cells or
enzymes.
2) Autonomously replicating circular , extra-chromosomal bacterial DNA used in gene manipulation.
3) Restriction enzymes.
4) Restriction endonucleases always cut DNA at a specific point by recognizing a specific sequences of
base pair known as recognition sequence.
5) DNA ligases
6) The ultimate step in the separation and isolation of DNA fragments through gel electrophoresis in
which separated bands of DNAs are cut out from the gel and extracted from the gel piece.
7) Cloning vectors are extra-chromosomal 'replicons' of DNA which can be isolated and can replicate
independently of the chromosome. DNA of interest can be cloned into the vector and replicated in host
cells
8) ORI point
9) Agrobacterium tumefaciens
10) Microinjection,biolistics(gene gun)
11) Polymerase Chain Reaction 12) Thermusaquaticus
13) Large scale biotechnological product involves the use of bioreactor.
14) Separation and purification
15) Eukaryotic cells have no restriction enzyme. It is present in prokaryotic cell (like bacteria) where
these act as defense mechanism to restrict the growth of bacteriophages.
2-Marks Questions
1) Enlist the core techniques that pave the way for modern biotechnology.
2) What is gene cloning?
3) Mention the three steps involve in genetically modifying an organism.
4) Why do bacteria possesses restriction enzyme ?
5) Mention one basic difference between restriction endonucleases and exonucleases.
6) What is a palindromic sequence? Give example.
7) What are ― sticky endsԡ and ―blunt ends ?
8) Mention the role of selectable marker in cloning vector.
9) What is insertional inactivation?
10) How can you make a bacterial cell competent to take up foreign DNA ?
11) Why is Agrobacterium-mediated genetic transformation described as natural genetic engineering in
plants?
6) A segment of double-stranded DNA in which the nucleotide sequence of one strand reads same in
reverse order to that of the complementary strand. (always read from the same direction)
7) Double stranded ends of a DNA molecule (without any overhangings) produced by the action of
certain restriction enzymes .-[blunt ends)/ Sticky ends - Double stranded ends] of a DNA molecule (with
overhangings) produced by the action of certain restriction enzymes
8) The selectable marker genes in a cloning vector allow for the selection and identification of bacteria
that have been transformed with a recombinant plasmid compared to nontransformed cells. Some of
the most common selectable markers are genes for ampicillin resistance (ampR) and tetracycline
resistance (tetR ) and the lacZ gene used for blue white selection.
9) Insertional inactivation refers to the loss of activity of the selectable marker genes due to the
insertion of foreign DNA within the coding sequence of the marker gene in transfected bacteria.
10) Calcium chloride treatment.
11) Agrobacterium tumefaciens is a pathogen of several dicot plants which exhibit natural genetic
engineering in plants.
Reasons:
• It is able to deliver a piece of DNA called ‘T-DNA’ to transform normal plant cell into a tumour cell.
• The DNA transforms the normal cells into tumour cells which direct them to produce the chemical
essential for the pathogen.
12) Thermus aquaticus produces a thermostable DNA polymerase enzyme which remains active during
the high temperature induced denaturation and separation of the double stranded DNA during PCR.
13) a compound called ethidium bromide stains DNA, which on irradiating with ultraviolet fluoresces
and gives orange light. Hence, DNA fragments appear as orange band in the presence of ethidium
bromide and UV.
3-Marks Questions:
1) Enlist the major steps in recombinant DNA technology.
2) Mention the steps involved in the separation and isolation of DNA fragments through agarose gel
electrophoresis.
3) Describe in brief the principle of DNA isolation through gel electrophoresis.
4) Highlight the salient features that are required to facilitate cloning into a vector.
5) Enumerate the major steps for isolation of DNA.
6) Draw a neat ,labeled diagram of (a) simple stirred tank bioreactor/ (b) sparged tank bioreactor.
7) What do you mean by replica plating?
8) What are the uses of embryonic stem cells?
Answers:
1) R-DNA Technology:
Restriction enzyme cuts double stranded DNA at its particular recognition sequence.
The cuts produce DNA fragments with cohesive ends
DNA from a plasmid was also cut by the same restriction enzyme
When two of the above mentioned DNA come together they can join by base pairing.
DNA ligase enzyme used to unite the backbones of the two DNA fragments, producing R-DNA
2) Agarose gel electrophoresis:
RNApolymerase promoter sequence
5) Major steps for isolation of DNA: Cell containing DNA is treated with lysozyme/cellulose/chitinase
DNA along with RNA, Protein, lipid are released
Treatment with RNAase, protease to remove RNA and Protein
Appropriate treatment to remove other impurities
Addition of chilled ethanol to get precipitation of purified DNA
6) Consult NCERT Textbook page number 204
7)
• In molecular biology and microbiology, replica plating is a technique in which one or more
secondary Petri plates containing different solid (agar-based) selective growth media (lacking
nutrients or containing chemical growth inhibitors such as antibiotics) are inoculated with the same
colonies of microorganisms from a primary plate (or master dish), reproducing the original spatial
pattern of colonies.
• The technique involves pressing a velveteen-covered disk, and then imprinting secondary plates
with cells in colonies removed from the original plate by the material. Generally, large numbers of
colonies (roughly 30-300) are replica plated due to the difficulty in streaking each out individually
onto a separate plate.
8) Embryonic stem cells are pluripotent and depending upon the type of stimulus given, these cells can
differentiate into about 200 different cell types present in the body of an adult human being. Thus ES
have tremendous potential for use in regenerative medicine to generate organs and tissues for
replacement of damaged or diseased ones in case of:
• Leukemia or cancerous blood cells.
• Heart diseases, cardiac tissue damage.
• Paralysis (spinal cord injury)
• Alzheimer’s, Parkinson’s, Huntington’s disease.
• Burns (damaged skin cells)
5-Marks Questions:
1) What do you mean by PCR? Briefly enumerate the major steps of PCR. Mention the utility of
PCR.
Ans: PCR is a cycle of three steps:
• DENATURATION - the strands of the DNA are melted apart by heating to 95°C.
• ANNEALING - the temperature is reduced to ~ 55°C to allow the primers to anneal to the target
DNA.
• POLYMERISATION/EXTENSION - the temperature is changed to the optimum temperature in
order for the DNA polymerase to catalyse extension of the primers, i.e. to copy the DNA
•
Additionally, the recombinant protein may not be secreted into the medium or its incorrect
folding and accumulation intracellularly may generate inclusion bodies.
Chapter-12 BIOTECHNOLOGY & ITS APPLICATION
Biotechnology is making Genetically modified organisms-microbes, plants, animals for
industrial production of Bio-Pharmaceuticals and other useful products.
Applications –
i) Diagnostic & therapeutic
ii) Genetically modified crops
iii) Waste treatment
iv) Energy production
v) Food processing
vi) Bioremediation
Application in agriculture
Genetically modified organisms (GMO)-Plants, bacteria, fungi, animals.whose genes are
altered by manipulation.
Transgenic crops(GMO) -Crops contain or express one or more useful foreign genes.
Advantages -i) More tolerant to stresses (heat, cold, draught).
ii) Pest resistants GM crops, reduce the use of Chemical pesticides. Eg- BTCotton
iii) Reduced post harvest losses. Eg- Flavr savr tomato.
iv) Enhance nutritional value of food. eg.- Golden Rice (Vitamin A enriched).
v) Increased efficiency of mineral use.
PEST RESISTANT PLANTS
Bt- cotton -BT stands for Bacillus thuringiensis (Soil Bacteria). Bacterium produces
proteins (Crystal Protein-cry I AC, cry II AB). A crystalliane insecticidal protein that kills the
insects.Hence cry-Genes have been introduced in plants to produce crystal proteins as
Protoxin (inactive toxin), which is converted to toxins in alkaline medium (i.e. in the gut of
insects) and cause death of the insect larva.
In medicine- genetically engineered insulin—
rDNA technology was applied in therapeutic application by generating genetically engineered insulin for
man. In 1983, Eli Lilly, an American company prepared 2 DNA sequences coding for chains A & B.
Human insulin consists of two short Polypeptide chains A & B being linked by disulphide bridges.In
man, Insulin secreted as Prohormone containing C peptides that is removed during maturation.
In rDNA technique, insulin could be generated by preparing two separate DNA sequences of A & B
chain which are incorporated into plasmids of E. coli to produce insulin chains.
Gene therapy
• Gene therapy involves correction of the gene defects in child or embryo.
• Adenosine deaminase deficiency is a kind of immuno-disorder caused by deletion of gene
coding for ADA.
• It can be cured by bone marrow transplantation or enzyme replacement therapy.
• A functional ADA-cDNA(through Retrovirus) is introduced in lymphocyte culture for genetic
infusion and transfered to the patient body for normal functioning.
Molecular diagnosis -Early & accurate detection of diseases substituting conventional diagnostic tecniques may be done by
2. To use proteins for treatment of disease.
3. To verify vaccine and chemical safety.
Biropiracy -- Some organizations and multinational companies exploit or patent bioresources of other
nations without proper authorization. Indian patent bill is there to prevent such unauthorized
exploitation.
GEAC- For validity of GM research and the safety of introducing GM organism
Three mark question
1) What is the main advantage of producing genetically engineered insulin?
Ans- i) Produces only A&B peptides ii) No C-Peptides produced iii)No need to remove CPeptides during maturation.
2) What are the advantages of Molecular diagnosis technique?
Ans- i) Accurate ii) disease can be detected at very early stage iii)Can be diagnosed even if
the number of pathogens is very low.
3)What are the potential risks ( Three ) of using GM food?
Ans – Potential risks- i) Products of transgene - allergic or toxic ii) Cause damage to natural
environment iii) Weeds also become resistant iv) Can endanger native species
4)What is hirudin? How do you get it?
Ans- Anti coagulant obtained from transgenic Brassica napus.
5) How does agro bacterium help to increase Tobacco production?
Ans –i) Introduction of Nematode specific gene.ii)Production of dsRNA(Sense and antiSense)
iii)Silence specific mRNA.
6) Why do farmers face the problems in Agro chemical based farming?
Ans – i) Too expensive ii) Conventional breeding procedure do not ensure increased
production.
7) Why should farmers in India cultivate GM crops?
Ans - Tolerant to stress,pest resistant,less post-harvest losses, increased mineral use
efficiency.
Five mark question
1)Explain the steps involved in the production of genetically engineered insulin?
Ans- i) Human insulin consists of 51 amino acids arranged in chains of A and B bearing 21
and 30 a. a respectively interconnected by disulphide bridges.
Diagram- Maturation of proinsulin into insulin after removal of c- peptide
ii) Insulin synthesized as prohormone has extra c -peptide which is removed during
maturation.
iii) In 1983 , Eli Lilly, American company prepared two DNA sequences similar to A and
B chains of
human insulin(humulin).
iv) Chain A and B extracted and combined by creating disulphide bonds.
Keywords of the chapter
Genetically Modified Organism(GMO), Bt cotton, insecticidal proteins, cry genes, pest
resistant plants, RNA interference(RNAi)/RNAsilencing, dsRNA, Genetically engineered
insulin, gene therapy, ADA deficiency , c DNA, Molecular diagnosis, transgenic animals, Bio
ethics, Genetic Engineering Approval Committee(GEAC), Bio piracy, Indian patent bill.
(HOTS) CHAPTER 12:
1.Name the disease in plants caused by Ti Plasmid?
Crown gall disease.
2. What is the main objective of Gene therapy in biotechnological techniques?
Gene therapy involves replacement of defective genes by normal genes.
3 Which organism is considered as Natural genetic engineer?
Gene therapy
8.The bacterium Bacillus thuringiensis provides the major source of insect
resistant gene-clarify.
Produces insecticidal protein i.e. ‘cry protein’ that kills certain insect pests.
The gene encoding for ‘ cry protein’ is isolated from bacteria & incorporated
in major crop plants as bio-pesticides.
9. 'RNAsilencing is a form of genomic defense’. Elucidate the statement taking
M. incognitia as an example.
RNA-interference technique is adopted to prevent infestation of nematode M.
incognitia in the roots of Tobacco plants .Nematode specific genes introduced
into host plants by complementary ds RNA developed through ‘transposons’ .
10. Identify a, b, c from the table given below:
Nematode specific gene+Agrobacterium
a
Host plant with nematode gene
ds DNA
b
a) sense RNA b) Anti sense RNA c)silencing mRNA
LIST OF TRANSGENIC PLANTS & ITS USES
Sl.
No.
01.
Transgenic plants
Application
Bt Cotton
02.
Flavr Savr Tomato
03.
Potato
04.
Brassica napus
Pest resistant(Cotton bollworm) ,
Herbicide tolerant, High yield
Improved nutrient quality(Increased
solid nutrient)
Increased nutritional quantity(Starch
content)
Hirudin protein prevents blood
c
Sl.
No.
01.
Transgenic
microorganisms
Bacillus thuringiensis
02.
Escherichia coli
03.
04.
05.
06.
Pseudomonas
fluorescence
Pseudomonas putida
Rhizobium meliloti
Trichoderma
07.
Tramates
Application
Produces cry protein as plant
insecticide
Produces human insulin,
interferons,interleukin
Prevents frost damage of fruits
Scavenging of oil spillage.
Nitrogen fixation by Nif gene
Biocontrol of fungal diseases in
plants.
Removal of lignin from wood
pulp.
Chapter 13 ORGANISMS AND POPULATIONS
Ecology
# It deals with the interaction Amongorganisms Between organisms &Physical environment.
Atmosphere Organism Organism plants,
Abiotic factors
Temperature, soil,
Biotic factors
Microorganisms,
water, light
Animals
Temperature
# Average temperature varies seasonally
# Organisms may be Eurythermal or Stenothermal
Eurythermal- wide range of temperature tolerance
Stenothermal-Narrow range of temperature tolerance
Water
# Influences life of organisms. No life without water.
# Productivity and distribution of plants are water dependent.
#Organisms may be Euryhaline or Stenohaline.
Euryhaline- Wide range of salinity tolerence
Stenohaline.Narrow range of salinity tolerance.
Light
# Photosynthesis and release of oxygen light dependent.
# Sciophytes need to use diurnal and seasonal light intensity of forage, migration and
reproduction.
Soil
# Nature and proportion of soil in a place depends on climate, weathering process and types
of soil.
# Soil composition, grain size and aggregation determine percolation and water holding
capacity of soil.
# Physical and chemical properties determine type of plants and Animals that survive in a
habitat.
suspention
organism
Migration
conformation
Adaptation
Regulation
# Organisms maintain homeostasis achieved by physiological and behavioral means
# Thermo regulation and osmoregulation.
Conformation
# Cannot maintain constant internal Environment
# Body temperature and osmotic concentration of body changes with ambient temperature
and concentration of medium.-Thermo confirmer and osmo confirmer
Migration
# Organism moves away temporarily to another habitat in stressful condition.
e.g.- Migratory birds like Siberian crane
Suspension
# Organisms suspend their metabolic activities during stressful condition
# Resume their function at the return of favorable conditions.
E.g. Hibernation (winter sleep) of Frog, Reptiles, Polar Bear etc
# Aestivation (summer sleep) in Snail and Fish.
# Seed dormancy.
Adaptation
# Morphological, physiological and behavioral changes that enable organisms to adjust to the
ever changing environment .
E.g. Kangaroo rat survives in desert conditions through internal oxidation of fat, removing
concentrated urine of limited quantity.
# Allen‘s rule-cold climate mammals have shorter ears and limbs to minimize heat loss.
# Polar mammals like seals have blubber to prevent heat loss.
# Burrowing habit to escape from heat
# Higher count of RBC, Hb(haemoglobin) at high altitudes.
Population attributes
Age pyramids
# Three ecological ages:
# Pre-reproductive, Reproductive and Post-Reproductive
# High proportion pre-reproductive individuals occur in Expanding population
# Pre-reproductive individuals are uniform in Stable population.
# Pre-reproductive individuals are less in Declining population.
Representation of age pyramids for human population
Post-Reproductive
Reproductive
Pre-Reproductive
DECLINING
EXPANDING
Population growth
Factors that affect the size of population
Food availability
Weather
Predation pressure
Competition
Density of population at any time at a given place depends on
Natality, Mortality, Emigration Immigration
Population growth models
STABLE
EMIGRATION
[E]
The characteristics of populations are shaped by the interactions between individuals and their environment •
Populations have size and geographical boundaries. –
The Density of a population is measured as the number of individuals per unit area. –
The Dispersion of a population is the pattern of spacing among individuals within the geographic boundaries. •
MEASURING DENSITY •
Density – Number of individuals per unit of area. •
Population will grow if B+I > D+E •
Population will shrink if B+I < D+E •
Population will be in equilibrium if B+I=D+E (1) Population
(a)
A population in an ecological sense is a group of organisms, of the same
species, which roughly occupy the same geographical area at the same time
(2) Population size
(a)
A population's size depends on how the population is defined
(b)
If a population is defined in terms of some degree of reproductive isolation,
then that population's size is the size of its gene pool
(c)
If a population is defined in terms of some geographical range, then that
population's size is the number of individuals living in the defined area
(3) Population density
(a)
Given that a population is defined in terms of some natural or arbitrarily
defined geographical range, then population density may be defined as simply
the number of individual organisms per unit area
(b)
(4) Patterns of dispersion
(a)
Individual members of populations may be distributed over a geographical
area in a number of different ways including
(i)
Cl
d di t ib ti ( tt ti )
Types of population interactions
INTERACTION
Mutualism
Predation
Parasitism
Commensalism
Competition
Ammensalism
SPECIES “ a”
+
+
+
+
-
SPECIES “ b”
+
0
0
Mutualism Both species benefited.
Lichens Relationship between Non-photosynthetic Fungi and photosynthetic
Algae or Cyanobacteria.
Mycorrhiza Asociation between Fungi and Higher Plants like Pinus.
Plants and insects for pollination
Orchid ophrys and male bee a good example for co-evolution of plants and
animals.
PREDATION
One species gets benefited and the other harmed.
Tiger and Deer
Snake and Frog
Herbivores and plants
C
titi
Parasitism
One species gets benefit and the other is harmed.
Parasites
Endoparasites
Liver fluke, Plasmodium
Ectoparasites
lice, ticks
Brood parasites
Koel
Adaptations of parasites
# Loss of sense organs
# Presence of adhesive organs or suckers
# Loss of digestive system
# High reproductive capacity.
Ammensalism
One species hurts the other but the other is not affected.
Penicillium secretes Penicillin and kill Bacteria but by this Penicillium does not benefit.
Algal bloom leads to death of fishes, but the death of fishes is of no use to the algal
bloom.
Commensalism
One species benefits and the other neither harmed nor benefited.
The cattle egret catches the insects disturbed by moving cattle, but the cattle neither harmed nor
benefited.
Another example
Clown fish gets protection from predators by close association with sea anemone, but the sea
anemone is not effected.
Short questions HOTS
1. Why is temperature considered to be the most relevant abiotic factor that influences life of organisms?
ecause it affects the enzyme activity.
2. During global warming which type of organism can cope up better – Eurythermal or stenothermal?
Why?
urythermal as it can tolerate wide range of temperature.
3. Why does the logistic growth curve becomes S shaped?
- Sigmoid curve, population becomes stable due to environmental resistance.
B
E
Ans. 1. Algae and Fungi in Lichens
2. Head Louse Humans
3. Hermit Crab and Sea Anemone
(i) Interaction of mutualism where the two species are equally benefited. Fungus provides protection,
helps in absorption of water and minerals, Algae provide food for the Fungus.
(ii) This is case of Parasitism where the louse is an ectoparasite. Parasite takes shelter on humans and
also derives nutrition.
(iii) It is commensalisms where one species is benefited and the other is neither benefited nor affected.
Sea
Anemone is benefited as it does not have to move to places rich in nutrients, while hermit crab is
neither
benefited nor harmed.
3. How does Ophrys get pollinated by bees?
Ans.1. Sexual deceit.
2. One petal resembles female.
3. Male pseudocoupulates with the flower.
4. Pollen grain transferred from one flower to another.
4. Biomass is a more meaningful measure of population size. Explain with an example.
Ans. (i) Population large Total number is not an easily adoptable measure. Counting takes long time or
practically impossible
(ii) There is no need to know the absolute population size for some investigations.
(iii) Number may sometimes be misleading eg. In a given area there are 200Parthenium plants and a
single banyan tree. Here biomass size of the banyan tree is much more than those of 200Parthenium
plants.
5. Give example of how plant protects themselves from the predators.
Ans. (i) Thorns.eg. – Rose, babool etc.
(ii) Chemicals that can kill the animals. eg.- Calotropis etc.
6. What is interference competition? Define competitive exclusion principles.
Ans. (i) Feeding efficiency may be reduced due to interference of another species. eg. –Tiger and deer.
(ii)Two closely related species need same resource can not co-exist indefinitely.
(5 Marks) Questions:
1.What are the different types of population growth pattern? Mention their differences.
Ans: a. Logistic and Exponential growth
b. S Shaped curve, J shaped curve. Limiting Factors, No-limiting Factors
2.With the help of age pyramids explain the nature of a population.
Ans: a. Pre-reproductive/ re-productive/ post-reproductive
b. increasing population/ stable population/ declining population
S.No.
Biogeographic zones
Biotic provinces
1.
Trans-Himalaya
Ladakh mountains, Tibetan plateau
2.
Himalaya
Northwest, West, Central and East Himalayas
3.
Desert
Thar, Kutch
4.
Semi-arid
Punjab plains, Gujarat Rajputana
5.
Western Ghats
Malabar plains, Western Ghats
6.
Deccan Peninsula
Central highlands, Chotta-Nagpur, Eastern highlands, Central
Plateau, Deccan South
7.
Gangetic plains
Upper and Lower Gangetic plains
8.
Coast
West and East coast, Lakshadweep
North-East
Brahmaputra valley, Northeast hills
Islands
Andaman and Nicobar
9.
10.
Source: Wildlife Protected Area Network in India: A Review, Wildlife Institute of India, 2000.
The exponential model of population describes an idealized population in an unlimited environment •
We define a change in population size based on the following verbal equation. Change in population = Births during – Deaths during size during time interval time interval time interval • Using mathematical notation we can express this relationship as follows: –
–
If N represents population size, and t represents time, then ΔNis the change in population size and Δtrepresents the change in time, then: •
ΔN/Δt = B‐D •
Where B is the number of births and D is the number of deaths We can simplify the equation and use r to represent the difference in per capita birth and death rates. •
ΔN/Δt = rN OR dN/dt = rN –
If B = D then there is zero population growth (ZPG). –
Under ideal conditions, a population grows rapidly. •
Exponential population growth is said to be happening LOGISTIC GROWTH RATE Assumes that the rate of population growth slows as the population size approaches carrying capacity, leveling to a constant level. S‐shaped curve CARRYING CAPACITY The maximum sustainable population a particular environment can support over a long period of time.
Population growth
(a) The simplest case of population growth is that which occurs when there exists no
limitations on growth within the environment
(b) In such situations two things occur
The population displays its intrinsic rate of increase
(i)
The population experiences exponential growth
(ii)
Intrinsic rate of population increase (rmax)
(a) Intrinsic rate of population increase is the rate of growth of a population when that
population is growing under ideal conditions and without limits, ie.as fast as it
possibly can
This rate of growth implies that the difference between the birth rate and death
(b)
rate experienced by a population is maximized
However, a population that is not growing maximally can still experience
(e)
exponential growth
(f)
"A population with a higher intrinsic rate of increase will grow faster than
one with a lower rate of increase. The value of rmax for a population is
K-selected characteristics; life history evolves in the context of
a complex interplay of factors."
Mishra is known as father of Ecology in India r
K
Unstable environment,
density independent
Stable environment, density
dependent interactions
Photo synthetically Loss as heat And light Active Radiation Organism size
Small
Variable
Large
constant
Energy used to make
each individual
Low
High
# Offspring produced
Many
Few
Timing of maturation
Early
Late
(with much parental care)
Life expectancy
Short(i.e. high mortality)
Long
Lifetime reproductive
events
One
More than one
Environment
Variable and unpredictable
Constant or variable but
predictable
Chapter-14:ECOSYSTEM
Ecology [Gkeek: oikos; home and logos; the study of ] – First
coined by Earnst Haechel (1869). Ecology therefore - study of an organism in its
natural home.
Odum (1963) defined ecology as the study of structure and function of nature or the study of
inter-relationships between organisms and their environment.
Inter relationship between components of ecosystem
Incident solar radiation (100%)
50% lost due to
50% is PAR
1-5%
Net Primary Productivity
0.8-4%
Producer
Primary consumer
Decomposition
Death
Secondary consumer
Tertiary consumer
Leaching
Detritus
Fragmentation
Respiratory Loss 0.2‐1% Catabolism
Humification
Mineralization
Bio geo chemical cycle
Vocabulary:
• Habitat: Environment in which a species normally lives or the location of a living
organism.
• Ecology: The Scientific Study of the Interactions between organisms and the
environment
• Abiotic: Non-living (ex. Temp, light, water, nutrients)
• Biotic: Living organisms (called biota)
• Population: A group of individuals of the same species living in a particular
geographic
area
•Ecosystem ecology: The emphasis is on energy flow and chemical cycling among
thevarious biotic and abiotic components.
•Biome: Any of the world’s major ecosystems, classified according to the
predominantvegetation and characterized by adaptations of organisms to that
environment. Terrestrial regions inhabited by certain types of life, especially
vegetation. eg. Deserts, grassland and forests.
• Biological diversity - variety of different species (species diversity), genetic
variability among individuals within each species (genetic diversity), and
variety of ecosystems (ecological diversity).
Biotic potential - maximum rate at which the population of a given species can
increase when there are no limits of any sort on its rate of growth.
Carrying capacity (K) - maximum population of a particular species that a given
habitat can support over a given period of time.
Competition - two or more individual organisms of a single species (intraspecific
competition) or two or more individuals of different species (interspecific competition)
attempting to use the same scarce resources in the same ecosystem.
Consumer - organism that cannot synthesize the organic nutrients it needs and
gets its organic nutrients by feeding on the tissues of producers or of other
consumers; generally divided into primary consumers (herbivores), secondary
consumers (carnivores), tertiary (higher-level) consumers, omnivores, and
detritivores (decomposers and detritus feeders).
Deforestation - removal of trees from a forested area without adequate replanting.
Desert - biome where evaporation exceeds precipitation and the average amount of
precipitation is less than 25 centimeters (10 inches) a year. Such areas have little
vegetation or have widely spaced, mostly low vegetation.
Desertification - conversion of rangeland, rain-fed cropland, or irrigated cropland to
desert like land, with a drop in agricultural productivity of 10% or more. It is usually
caused by a combination of overgrazing, soil erosion, prolonged drought, and
climate change.
Ecological diversity - the variety of forests, deserts, grasslands, oceans, streams,
lakes, and other biological communities interacting with one another and with their
nonliving environment.
Ecological niche - total way of life or role of a species in an ecosystem. It includes
all physical, chemical, and biological conditions a species needs to live and
reproduce in an ecosystem.
Ecology - study of the interactions of living organisms with one another and with
their nonliving environment of matter and energy.Study of the structure and function
of nature.
Environmental degradation - depletion or destruction of a potentially renewable
resource such as soil, grassland, forest, or wildlife by using it at a faster rate than it is
naturally replenished. If such use continues, the resource can become nonrenewable
on a human time scale or nonexistent (extinct).
Extinction - complete disappearance of a species from the earth. This happens
Immature community - community at an early stage of ecological succession. It
usually has a low number of species and ecological niches and cannot capture and
use energy and cycle critical nutrients as efficiently as more complex, mature
ecosystems.
Keystone species - species that play roles affecting many other organisms in an
ecosystem.
Limiting factor - single factor that limits the growth, abundance, or distribution of
the population of a species in an ecosystem.
Mature community - fairly stable, self-sustaining community in an advanced stage
of ecological succession; usually has a diverse array of species and ecological
niches; captures and uses energy and cycles critical chemicals more efficiently than
simpler, immature communities.
Native species - species that normally live and thrive in a particular ecosystem.
Pioneer community - first integrated set of plants, animals, and decomposers
found in an area undergoing primary ecological succession.
Pioneer species - first hardy species, often microbes, mosses, and lichens, that
begin colonizing a site as the first stage of ecological succession.
Primary succession - sequential development of communities in a bare area that
has never been occupied by a community of organisms.
Secondary succession - sequential development of communities in an area in
which natural vegetation has been removed or destroyed but the soil is not
destroyed.
QUESTIONS
[2 MARKS QUESTIONS]
Q1.What are decomposers? Write their function.
Ans-a)Saprotrophs feed on dead bodies of organisms, b) Decomposition and mineralization.
Q2.What is the difference between gaseous and sedimentary cycle?
Ans-a) Gaseous-Reservoir in atmosphere ,Nitrogen cycle b) Sedimentary-Soil,eg-phosphorus.
Q3.Why is the length of a food chain in an ecosystem generally limited to 3-4 trophic levels?
Ans –As 90% energy is lost in the form of heat from one trophic level to another, residual
energy decreases drastically within 2-3 trophic levels.
Q4.What are the differences between detritus and grazing food chains?
Ans-a) Begins with Detritus-dead and decaying organic matter. b) Grazing-Begins with living
green plants.
Q5.What are the two basic catagories of ecosystem? Give example.
Ans-a) Terrestrial-Forest, grassland, desert. b) Aquatic-Pond, lake, sea, ocean
Q6.Mention two factors by which productivity is limited in an aquatic ecosystem.
Ans-a) Light-decreases with increasing water depth. b) Nutrient –Limiting factor in Deep
Ocean
Q7.What is food chain? Give an example.
Ans-a) Food and feeding relation among organisms makes a chain like structure b) Grass—
Ans-a) climatic factor – i)temp ii) soil b) chemical quality of detritus . Higher temp and moist
condition – high rate of decomposition .Dry soil , High temp – Low rate
Q3) What are ecological pyramids ? Mention its limitations .
Ans –a) Arrangement of trophic levels from producers to top carnivores forms pyramid like
structure 3 types – i) Pyramid of number ii) Biomass iii) Energy
Limitations – i) Assumes simple food chain ii) Single species may operate at two or more
trophic levels.
Q4 ) Explain carbon cycle with ray diagram .
Ans – Given in text.
Q5 .Describe pond as an ecosystem .
Ans- Pond has biotic and abiotic components
a) Biotic – Phytoplankton ,Zooplankton , small fishes , large fishes , frogs , snake ,etc.
b) Abiotic - water , dissolved organic and inorganic substances ,sunlight , temp .
Phytoplankton (microscopic plants) – producers . Zooplankton (microscopic animals) –
primary consumers .Small fishes - secondary consumers .Large fishes , frog, snails – tertiary
consumers.
[5 Marks Questions]
Q1. Describe the major components of ecosystems.
Ans- a) Biotic-i) Producer-green plants. ii) Consumers-primary, secondary,tertiary and
decomposers. b) Abiotic-i) Physical and climatic factors-soil, temperature,light, humidity. ii)
Chemical factors-inorganic chemical substances (sodium, potassium, nitrogen etc.) organic
substances-(humus, protein, fat etc.)
Q2. Give an account of energy flow in an ecosystem.
Ans- Rate of energy transfer between the organisms of different trophic levels is called
energy flow. Energy flow is unidirectional, 10% loss of energy in each trophic levels. 2-10%
PAR captured by green plants.Energy flow diagram from the text.
Q3.What is xerosere?
Describe the process of succession on a bare rock. Ans-a) Succession on bare rock. b) Steps
in Xerosere i) Lichens-Pioneer Community. ii) Mosses iii) Herbs iv) Shrubs v) Trees-Climax
community.
Chapter-15: BIODIVERSITY AND CONSERVATION
Biodiversity is defined as the totality of genes, species and ecosystems of a given region, It is the
variety and variability of life form (all animals, plants and microbes on earth) and the ecological
complexes in which they occur.The term was first coined by Walter G. Rosen(1985),however the term
was popularized by the American sociobiologist Edward Wilson(1988)
Hierarchial levels of Biodiversirty:
1)Species Diversity
2)Genetic Diversity and.
3)Ecosystem/Community/Habitat Diversity
Patterns of Biodiversity:
1) Latitudinal gradients – species diversity decreases, from equator to poles. Tropics (23.50N
-23.50S) show richest species diversity. Speciation is generally a function of time. Temperate
region is subjected to glaciations. Tropical regions remained relatively undisturbed for millions
of years and thus had a long evolutionary time for species diversification. Tropical
environments are less seasonal, relatively more constant and predictable. Constant
environment facilitates niche specialisation and lead to greater species diversity. Tropical
latitudes also get huge solar radiations which promote higher productivity.
2) SPECIES – Area relationships :
Arrhenius (1921) concluded that the number of species increases continuously less as the area increases. This phenomenon is known as the species/area relationship (SAR). This is reflected in the z
quantitative formula S = cA , in which S represents the number of species and A the size of the area. The constant c is an empirically determined multiplier that varies among taxa and areasThe exponent z varies according to the topographic diversity, the isolation of the area and the mobility of the taxon. It is usually higher* for islands (around 0.3) than for the mainland (commonly assumed less that 0.2). (* the lower z, the less space isneededto capture a greater number of species.)
ALEXANDER VON HUMBOLDT observed within a region species richness increased with increasing
explored area but only up to a limit.The relation between species richness and area for a wide variety of
taxa turns out to be a rectangular hyperbola. On a logarithmic scale the relationship is a straight line
described by the equation
LogS = logC +Z log AWhere S= species richness, A = Area, Z = slope of the line(regression
coefficient),C = Y- intercept.It has been noted that regardless of the taxonomic group or region the
slope of the regression line are amazingly similar. However, for a very large area like the entire
continent the slope of the line is steeper.
Loss of biodiversity:
Loss of biodiversity in a region may lead to
1)decline in plant production
2)lowered resistance to environmental changes such as drought.
3)increased variability in certain ecosystem processes such as plant productivity, water use, pest &
disease cycles.
Major causes of biodiversity loss:
measures to save from extinction within their natural habitat( in wildlife sanctuaries, national parks &
biosphere reserves, sacred groves /lakes-i.e. in protected areas)
Biodiversity hotspots – regions with very high levels of species richness and endemism. Norman
Myers developed the concept of hotspots in 1998 to designate priority areas for insitu conservation.
They are the most threatened reservoir of biodiversity on earth. In India 2 hotspots are there,
eg.Western ghats, and the Eastern Himalayas.
Ex-situ Conservation –Threatened animals& plants are taken out from their natural habitat&
placed in a setting where they can be protected and given care as in botanical gardens, zoological
gardens, seed/pollen/gene banks etc.
Efforts to conserve biodiversity:
Convention on Biological Diversity(CBD)
The three main goals of CBD are
1)Conservation of biological diversity
2)Sustainable use of components and
3)Fair and equitable sharing of benefits
Indian efforts:
Taking cognizance of the provisions of the CBD,India has enacted an umbrella legislation called the
Biological Diversity Act,2002 and also notified the Biological Diversity Rulkes,2004.Its primary aim is to
endorse the main goals of CBD suiting to India’s national needs and circumstances.
India will host the 11th Conference of Parties(COP) (known as RIO+20)in October2012.
Drivers of biodiversity loss
The main threats to biodiversity are one or more of the following developments:
•Human population growth- means growing demands for space and food.
•Intensive agriculture - encroach on habitats.
•Extension of road, rail and electricity networks - fragments habitats and
scares away some species.
•Overexploitation - we consume too much of a species or goods that ecosystems provide.
includes excessive hunting, collecting and trade in species and parts of species.
•Pollution- affects the health of animals and plants as much as human health.
Environmental disasters such as oil spills have devastating consequences for
birds and the marine fauna and flora.
•Climate change – global rise in temperature between 1.4° and 5.8° Celsius and the sea level
by between 9 and 88 cm. Many species will not be able to adapt or move to other regions in
next century.
•Invasive alien species - species that enter an ecosystem where they don't
occur naturally and then thrive and overwhelm endemic species.
•The tasty Nile perch was introduced to Lake Victoria in Africa in 1954 and caused
the extinction of more than 200 endemic fish
Endangered species a species that is in danger of extinction throughout all or a significant
portion of its range.
Ex situ conservation- removal of germplasm resources (seed, pollen,
i di id l
i
) f
th i
i i l h bit t
t l
i
t K
i
are Near Threatened).
Species diversity-The number and variety of species found in a given area in a region.
Table 1. Comparison Between the Number of Species in India and the World.
Group
Number of species
Number of species
SI/SW
in India (SI)
in the world (SW)
(%)
_____________________________________________________________________
Mammals
350(1)
4,629(7)
7.6
Birds
1224(2)
9,702(8)
12.6
Reptiles
408(3)
6,550(9)
6.2
Amphibians
197(4)
4,522(10)
4.4
Fishes
2546(5)
21,730(11)
11.7
Flowering Plants
15,000(6)
250,000(12)
6.0
_____________________________________________________________________
Table 2.Globally Threatened Animals Occurring in India by Status Category.
Group
Endangered
1994 IUCN Red List Threat Category
Vulnerable
Rare
Indeterminate
Insufficiently
TOTAL
Known
_____________________________________________________________________________________________
Mammals
13
20
2
5
13
53
Birds
6
20
25
13
5
69
Reptiles
6
6
4
5
2
23
Amphibians
0
0
0
3
0
3
Fishes
0
0
2
0
0
2
Invertebrates
1
3
12
2
4
22
_____________________________________________________________________________________________
TOTAL
26
49
45
28
24
172
Source: Groombridge, B. (ed). 1993. The 1994 IUCN Red List of Threatened Animals. IUCN,
Gland, Switzerland and Cambridge, UK.lvi +
Table 3.Summary of Plant Conservation Status Information at WCMC.
Source: WCMC Species Unit.\
Questions:
Q1. Define Biodiversity.
Ans-totality of genes, species and ecosystems of a given region
Q2.What is ecosystem diversity?
Ans.-No. of habitats or ecosystem in a given region of the biosphere.
Q3.Expand the term IUCN.
Ans. International Union for Conservation of Nature and Natural resources.
Q4.Who popularized the term biodiversity?
Ans .Edward Wilson
Q5.Can you mention the estimated number of species so far identified on earth?
Ans 1.7 to1.8 million
Q6. Establish the relationship between species richness and explored area
Ans-.(comment on the species – area relationship curve).
Q7.”Plots with more species showed less year to year variation in total biomass”-who showed this?
Ans- (David Tilman)
Q8.Who proposed the ‘Rivet popper hypothesis’? Comment on the major postulate of this hypothesis.
Ans- (Paul Ehrlich)
Q9.Mention the major causes behind biodiversity loss.
Ans-refer study material
Q10. Why should we conserve biodiversity?
Ans- (comment on the broad/narrow utilitarian and ethical value of biodiversity)
Q11.What do you mean by the term ‘ecosystem services’?
Ans- refer concept map
Q15.Can you mention some national and international efforts towards biodiversity conservation?
Q16. Write short notes on i) sacred groves and ii) traditional ecological knowledge.
Ans- refer NCERT text book
Chapter – 16: Environmental Issues
Pollution: Any undesirable change in physical, chemical or biological characteristics of air, land, water
or soil which harms the human beings.
POLLUTION
AIR POLLUTION WATER POLLUTION SOIL POLLUTION NOISE POLLUTION
Pollutants: Agents that bring about pollution eg. smoke, dust, pollen, chemical pollutants, wastes
from hospitals E-wastes etc
Advantage of CNG over diesel
• CNG burns most efficiently.
• Cheaper cannot be siphoned.
• Cannot be adulterated.
Problems in use of CNG
• Difficulty in laying down pipelines. Non-assurance of uninterrupted supply
Steps taken in Delhi to reduce pollution.
• Phasing out old vehicles.
• Use of unleaded petrol.
• Use of low sulphur Petrol and Diesel.
• Use of catalytic converters in vehicles Application of stringent pollution level norms for
vehicles.
Noise pollution
• It is undesirable high level of sound.
Harmful effects of noise pollution
• Psychological and Physiological disorders
• Damage of eardrums and hearing ability
• Cause sleeplessness, increased heartbeat altered breathing pattern, stress etc.
Steps to be taken to control noise pollution
• Use of sound absorbent materials or by muffling noise in industries
• Demarcation of horn free zones around hospitals and schools.
• Permissible sound levels of crackers,
• Timings after which Loudspeakers cannot be played
Water pollution
Deterioration in water quality due to physical, chemical or biological factor.
Sources of water pollution
a)Domestic sewage: Includes waste water from residential & public sewage system & contains
suspended solids(sand,silt & clay), colloids(faecal matter, microbes, paper & cloth fibres) , dissolved
materials(Nitrates, Ammonium phosphate, sodium and calcium salts) & biodegradable organic
wastes.
b) Industrial wastes
Includes heavy metals released along with waste water eg., Mercury , DDT which increases
toxicity level of water affecting living bodies and results in biomagnification.
BOD
Biological Oxygen Demand (BOD) indicates the amount of dissolved oxygen utilised by the
microorganisms for oxidising the organic matter present in the water body. Greater the organics,
greater would be the pollution and lesser the dissolved oxygen.
Water
Zooplankton
Small Fish
Large Fish
Fish-eating Birds
0.0003 ppm
0.04 ppm
0.5 ppm
2 ppm
5 ppm
Eutrophication
Defined as Natural ageing of lake by biological enrichment of its water. Life supportive water in
young lakes encourage growth of aquatic life & simultaneously deposition of organic remains at
the bottom . Eventually floating plants grow in raised water temperature resulting in blockade of
surface water that accelerates ageing called as eutrophication.
Cultural or accelerated eutrophication
Acceleration of ageing process of a lake by effluents from industries and homes.
Integrated waste water treatment in arcata
It consist of two steps
a) Conventional sedimentation, filtering and chlorine treatment,
b) Passing this water through marshes for neutralization absorption and assimilation of pollutants.
c) Upkeep of this project by FOAM (Friends of Arcata Marsh).
SOLID WASTES
Biodegradable Recyclable Non‐Biodegradable
Ecological sanitation (Ecosan)
A sustainable system for handling human excreta without using water but with composting
method.Advantages of ecosan
a) Wastage of water is reduced
b) Practical and efficient
c) Hygienic and cheap
d) Excreta can be recycled and used as natural fertilizer.
Hospital wastes
Syringes, discarded medicines, Used gloves, Post-operative materials etc.
Should be treated before disposing off.
E-wastes
• Unused or damaged computers, calculators, mobile phones etc.
• Developed countries have plants for recycling e-wastes for recycling of metals.
• In developing countries e-wastes are buried in landfills or incinerated.
Agro chemicals
• Chemicals used in agricultural fields, Fertilizers, pesticides, weedicides etc.
• They are toxic to even non target organisms.
• Excess fertilizers cause Eutrophication.
• They cause soil pollution
Advantages of organic farming
• Economical Wastes do not get accumulated but recycled
• Does not cause Eutrophication
Radioactive wastes
Green House Gases:-Carbon dioxide, methane, Chlorofluorocarbon
(CFC),Perfluromethane(CF4), Nitrous oxide(N2O) etc.
Harmful effect is global warming, increase in sea level
etc.
Ozone depletion
Ozonosphere protects earth from harmful radiation. In stratosphere,photodissociation results in
ozone formation that dissipates the energy of UV radiation . O 3
O 2 +O
UV
CFC produces active chlorine in presence of UV radiation & depletes ozone layer
.
UV-C
CFCl3
CFCl2+Cl
UV-C
CFCl2
CFCl+Cl
Cl+O 3
ClO +O2
C lO +O 3
Cl +2O 2
Triatomic molecule of oxygen. . •
•
•
•
•
Found in stratosphere of atmosphere.
CFCs discharged from lower atmosphere move upward .
UV rays act on these CFCs and release chlorine atoms.
Chlorine degrades ozone and release molecular oxygen.
This process is irreversible and thus ozone is depleted.
OZONE HOLE
Reference Fig 16.8 NCERT
Soil erosion
The removal of top fertile layer due to human activities
Reasons: • Over cultivation
O
i
• Loss of biodiversity
• Damage to hydrological cycle
• Leads to soil erosion
• Desertification of land
Reforestation
• Restoring forest that was existing earlier
• E.g. Observing Van-Mahotsavas
• It also occurs naturally
Afforestation
• Developing a forest in a new area where no such forest existed in that area.
A case study of people’s participation in forest conservation
A king of Jodhpur wanted to arrange wood for his new palace in 1731.
Few Bishnois hugged the trees and asked to cut them first rather than cutting trees.
365 persons lost their lives in this act
A small temple is now present there in remembrance of this act
Amrita Devi Bishnoi Wild Life Protection Award is instituted for individuals of rural areas who take
keen interest in protecting wild life.
Chipko movement
It was started by local women of Garhwal, They hugged the trees to protect them from the axes of
contractors.
Joint forest management (jfm)
• Strategy Government of India in 1980
• Local communities worked with the government to save the forest.
• Communities get forest products for encouragement.
Environmental issues
Very short answer type questions (1mark)
1. What is meant by algal blooms? What is its significance?
Ans. Excess growth of certain phytoplankton due to excess nutrients in water causes Deteriorates
water quality, leads to fish mortality.
2. Define eutrophication.
Ans. Nutrient enrichment in water bodies leading to depletion of oxygen and loss of life supporting
Environment.
3. What is bio magnification?
Ans. Increase in the concentration of certain toxic chemicals at successive trophic levels.
4. What is BOD?
Ans. Biological Oxygen Demand is the measure of organic matter in any water sample.
5. What is the effect of DDT in birds?
Ans. DDT disturbs calcium metabolism in birds, thinning of egg shell and premature breaking of
Eggs lead to decline in bird population.
6. What do you understand by ‗Ecosan‘?
Ans Ecosanare the toilets which use compositing method for ecological sanitation
of bird population.
Short answer type questions (2 marks)
1. Mention the harm caused by fine particulate matter to human beings?
Ans. (i) Cause respiratory problems
(ii) Irritation of eyes
(iii) Inflammation of lungs
(iv) Premature death.
2. Differentiate between biodegradable and non-biodegradable wastes.
Biodegradable wastes
Non-Biodegradable wastes
*Can be broken down into harmless simple
*Cannot be broken down by microbes and get
Compounds by the action of decomposers.
accumulated in the biosphere
*Can be used as manure
*Enter the food chain
*Cause little pollution
*Cause bio magnifications
3. Describe Chipko Movement.
Ans. It was launched in Garwhal, Himalayas by Shri Sunder LalBahuguna in 1974.
Local women showed enormous bravery in protecting the trees from the axes of the contractors
by hugging them.
4. What are the advantages of Organic farming?
Ans. Economical procedure as recycling takes place.
Waste not accumulated but recycled
Efficiency and utilization of resources increased
Does not lead to eutrophication.
5. Write an account on Ecological sanitation (Ecosan).
Ans.A sustainable system for handling human excreta, using dry composting toilets. Practical,
Hygienic, efficient and cost-effective solution to human waste disposal Human excreta can be
Recycled into manure Used in Kerala and Sri Lanka.
6. How do radioactive wastes cause damage to living organism?
Ans. Cause mutations in living organisms at a very high rate. Lethal in high doses Causes cancer
and other disorders.Reduces the vegetation cover.
7. What is ecological sanitation? What are its advantages?
Ans. It is sustainable system for handling human excreta without using water but by composting
Method.
Advantages
Hygienic, practical and efficient, Conserves water can be recycled and, Acts as a natural fertilizer.
Short answer type questions (3 marks)
1 Mention harmful effects of noise pollution on human health
Low Sulphur Diesel- Reduces sulphur pollution in air
Four stroke engines to reduce emission of unburnt hydrocarbons.
Tube-Ups to increase air-fuel ratio and help in better combustion.
Catalytic Converters to reduce pollution.
CNG to reduce pollution and conserve fossil fuels.
4. Mention the adverse effects agrochemicals.
Ans. They are toxic to non-target organisms. They cause soil pollution Excess fertilizers cause
eutrophication.
5. Write a short note on ozone depletion.
Ans. Ozone found in stratosphere. CFCs discharged from lower atmosphere move upward. In
stratosphere UV rays act on these CFCs release chlorine atoms. Chlorine degrades ozone and
release molecular oxygen (O3O2). In this reaction chlorine acts, as catalyst and loss ozone is
irreversible.
6. Mention the Supreme Court directions to the Government to reduce pollution.
Ans. Switch over to CNG in public transport system
Enforcement of Euro II norms for vehicles.
Compulsory periodic check-up of pollution.
Use of unleaded petrol Low sulphur petrol and diesel
Catalytic converters in vehicles
Phasing out of old vehicles.
Long answer type questions (5marks)
1. a) Explain the functioning of electrostatic precipitator with the help of a diagram.
b) Mention the consequence if the electrostatic precipitator does not work in a power plant.
Ans. Used for removing particulate air pollutants.
Removes about 99 of the particulate pollutants from the exhaust of thermal power plants.
Electrode wires that are maintained at several thousand volts, which release electrons.
Electrons become attached to dust particles giving a net negative charge.
Collecting plates are grounded and attract the charged dust particles.
Velocity of air between the plates must be low enough to allow the dust particles to fall.
If electrostatic precipitator of a thermal plant stops working, all the particulate pollutants get
released and pollute the air.
Discharge corona
IMPORTANT LEGISLATIONS FOR ENVIRONMENTAL PROTECTION
Sl. No.
01.
02.
03.
04.
05.
06.
Environmental Act
The Environment
Protection Act,1986
The Air (Prevention &
control) Act, 1981
The Water (Prevention
& control) Act, 1974
The Insecticide Act,
1968
Montreal Protocol
National Forest
Policy,1988
Kyoto Protocol,1977
07.
Application
Protect & control the quality of
environment
Protect & control of air pollution
Protect & control of water pollution to safe
guard water resources
Control & regulation of safe distribution &
use of insecticides
Control on emission of ozone depleting
substances
Restriction of forest cover for plain land &
hills
Reducing overall greenhouse gas emission
Photochemical oxidation (SMOG) :
•
•
Secondary air pollutants are produced from primary pollutants by
photochemical oxidation . eg.,Olefins, aldehydes, Peroxyacetyl Nitrate(PAN)
Photochemical Smogs are formed by following reactions:
N2 + O2
2NO (From vehicle exhaust)
2NO + O2
2NO2
UV
NO2
NO + O
O +O2
O3
NO +O3
NO2 +O2
HC +NO + O2
NO2 +PAN (Peroxyacetyl nitrate)(SMOG)